cons_bounddisjunction.c

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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*                                                                           */
/*                  This file is part of the program and library             */
/*         SCIP --- Solving Constraint Integer Programs                      */
/*                                                                           */
/*    Copyright (C) 2002-2018 Konrad-Zuse-Zentrum                            */
/*                            fuer Informationstechnik Berlin                */
/*                                                                           */
/*  SCIP is distributed under the terms of the ZIB Academic License.         */
/*                                                                           */
/*  You should have received a copy of the ZIB Academic License              */
/*  along with SCIP; see the file COPYING. If not email to scip@zib.de.      */
/*                                                                           */
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/**@file   cons_bounddisjunction.c
 * @brief  constraint handler for bound disjunction constraints \f$(x_1 \{\leq,\geq\} b_1) \vee \ldots \vee (x_n \{\leq,\geq\} b_n)\f$
 * @author Tobias Achterberg
 * @author Marc Pfetsch
 */

/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/

#include <assert.h>
#include <string.h>
#include <limits.h>
#include <ctype.h>

#include "scip/cons_bounddisjunction.h"
#include "scip/cons_quadratic.h"
#include "scip/cons_linear.h"
#include "scip/cons_logicor.h"
#include "scip/cons_setppc.h"
#include "scip/pub_misc.h"

/**@name Constraint handler properties
 *
 * @{
 */

#define CONSHDLR_NAME          "bounddisjunction"
#define CONSHDLR_DESC          "bound disjunction constraints"
#define CONSHDLR_ENFOPRIORITY  -3000000 /**< priority of the constraint handler for constraint enforcing */
#define CONSHDLR_CHECKPRIORITY -3000000 /**< priority of the constraint handler for checking feasibility */
#define CONSHDLR_PROPFREQ             1 /**< frequency for propagating domains; zero means only preprocessing propagation */
#define CONSHDLR_EAGERFREQ          100 /**< frequency for using all instead of only the useful constraints in separation,
                                         *   propagation and enforcement, -1 for no eager evaluations, 0 for first only */
#define CONSHDLR_MAXPREROUNDS        -1 /**< maximal number of presolving rounds the constraint handler participates in (-1: no limit) */
#define CONSHDLR_DELAYPROP        FALSE /**< should propagation method be delayed, if other propagators found reductions? */
#define CONSHDLR_NEEDSCONS         TRUE /**< should the constraint handler be skipped, if no constraints are available? */

#define CONSHDLR_PRESOLTIMING            SCIP_PRESOLTIMING_FAST
#define CONSHDLR_PROP_TIMING             SCIP_PROPTIMING_BEFORELP

#define QUADCONSUPGD_PRIORITY    500000 /**< priority of the constraint handler for upgrading of quadratic constraints */

/**@} */

/**@name Event handler properties
 *
 * @{
 */

#define EVENTHDLR_NAME         "bounddisjunction"
#define EVENTHDLR_DESC         "event handler for bound disjunction constraints"

/**@} */

/**@name Conflict handler properties
 *
 * @{
 */

#define CONFLICTHDLR_NAME      "bounddisjunction"
#define CONFLICTHDLR_DESC      "conflict handler creating bound disjunction constraints"
#define CONFLICTHDLR_PRIORITY  -3000000

/**@} */

/**@name Default parameter values
 *
 * @{
 */

#define DEFAULT_CONTINUOUSFRAC      0.4 /**< maximal percantage of continuous variables within a conflict */

/**@} */

/**@name Age increase defines
 *
 * @{
 */

/* @todo make this a parameter setting */
#if 1 /* @todo test which AGEINCREASE formula is better! */
#define AGEINCREASE(n) (1.0 + 0.2*n)
#else
#define AGEINCREASE(n) (0.1*n)
#endif

/**@} */


/**@name Comparison for two values
 *
 * @{
 */

#ifdef SCIP_DISABLED_CODE /* These only work if one also passes integral values in case of integral variables. This is not always the case and not even asserted. */
/** use defines for numeric compare methods to be slightly faster for integral values */
#define isFeasLT(scip, var, val1, val2) (SCIPvarIsIntegral(var) ? (val2) - (val1) >  0.5 : SCIPisFeasLT(scip, val1, val2))
#define isFeasLE(scip, var, val1, val2) (SCIPvarIsIntegral(var) ? (val2) - (val1) > -0.5 : SCIPisFeasLE(scip, val1, val2))
#define isFeasGT(scip, var, val1, val2) (SCIPvarIsIntegral(var) ? (val1) - (val2) >  0.5 : SCIPisFeasGT(scip, val1, val2))
#define isFeasGE(scip, var, val1, val2) (SCIPvarIsIntegral(var) ? (val1) - (val2) > -0.5 : SCIPisFeasGE(scip, val1, val2))
#else
#define isFeasLT(scip, var, val1, val2) SCIPisFeasLT(scip, val1, val2)
#define isFeasLE(scip, var, val1, val2) SCIPisFeasLE(scip, val1, val2)
#define isFeasGT(scip, var, val1, val2) SCIPisFeasGT(scip, val1, val2)
#define isFeasGE(scip, var, val1, val2) SCIPisFeasGE(scip, val1, val2)
#endif
/**@} */


/** constraint handler data */
struct SCIP_ConshdlrData
{
   SCIP_EVENTHDLR*       eventhdlr;          /**< event handler for events on watched variables */
};

/** bound disjunction constraint data */
struct SCIP_ConsData
{
   SCIP_VAR**            vars;               /**< variables of the literals in the constraint */
   SCIP_BOUNDTYPE*       boundtypes;         /**< types of bounds of the literals (lower or upper bounds) */
   SCIP_Real*            bounds;             /**< bounds of the literals */
   int                   varssize;           /**< size of vars, boundtypes, and bounds arrays */
   int                   nvars;              /**< number of variables in the constraint */
   int                   watchedvar1;        /**< position of the first watched variable */
   int                   watchedvar2;        /**< position of the second watched variable */
   int                   filterpos1;         /**< event filter position of first watched variable */
   int                   filterpos2;         /**< event filter position of second watched variable */
};

/**@name  Local methods
 *
 */

/** adds rounding locks for the given variable in the given bound disjunction constraint */
static
SCIP_RETCODE lockRounding(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint */
   SCIP_CONSDATA*        consdata,           /**< bound disjunction constraint data */
   int                   pos                 /**< position of the variable in the constraint */
   )
{
   assert(consdata != NULL);
   assert(0 <= pos && pos < consdata->nvars);

   if( consdata->boundtypes[pos] == SCIP_BOUNDTYPE_LOWER )
   {
      /* rounding down may violate the constraint */
      SCIP_CALL( SCIPlockVarCons(scip, consdata->vars[pos], cons, TRUE, FALSE) );
   }
   else
   {
      /* rounding up may violate the constraint */
      SCIP_CALL( SCIPlockVarCons(scip, consdata->vars[pos], cons, FALSE, TRUE) );
   }

   return SCIP_OKAY;
}

/** removes rounding locks for the given variable in the given bound disjunction constraint */
static
SCIP_RETCODE unlockRounding(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint */
   SCIP_CONSDATA*        consdata,           /**< bound disjunction constraint data */
   int                   pos                 /**< position of the variable in the constraint */
   )
{
   assert(consdata != NULL);
   assert(0 <= pos && pos < consdata->nvars);

   if( consdata->boundtypes[pos] == SCIP_BOUNDTYPE_LOWER )
   {
      /* rounding down may violate the constraint */
      SCIP_CALL( SCIPunlockVarCons(scip, consdata->vars[pos], cons, TRUE, FALSE) );
   }
   else
   {
      /* rounding up may violate the constraint */
      SCIP_CALL( SCIPunlockVarCons(scip, consdata->vars[pos], cons, FALSE, TRUE) );
   }

   return SCIP_OKAY;
}

/** catches the events on a single variable of the bound disjunction constraint */
static
SCIP_RETCODE catchEvents(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint */
   SCIP_CONSDATA*        consdata,           /**< bound disjunction constraint data */
   SCIP_EVENTHDLR*       eventhdlr,          /**< event handler to call for the event processing */
   int                   pos,                /**< position of the variable in the constraint */
   int*                  filterpos           /**< pointer to store position of event filter entry, or NULL */
   )
{
   assert(consdata != NULL);
   assert(0 <= pos && pos < consdata->nvars);

   if( consdata->boundtypes[pos] == SCIP_BOUNDTYPE_LOWER )
   {
      SCIP_CALL( SCIPcatchVarEvent(scip, consdata->vars[pos], SCIP_EVENTTYPE_UBTIGHTENED | SCIP_EVENTTYPE_LBRELAXED,
            eventhdlr, (SCIP_EVENTDATA*)cons, filterpos) );
   }
   else
   {
      SCIP_CALL( SCIPcatchVarEvent(scip, consdata->vars[pos], SCIP_EVENTTYPE_LBTIGHTENED | SCIP_EVENTTYPE_UBRELAXED,
            eventhdlr, (SCIP_EVENTDATA*)cons, filterpos) );
   }

   return SCIP_OKAY;
}

/** drops the events on a single variable of the bound disjunction constraint */
static
SCIP_RETCODE dropEvents(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint */
   SCIP_CONSDATA*        consdata,           /**< bound disjunction constraint data */
   SCIP_EVENTHDLR*       eventhdlr,          /**< event handler to call for the event processing */
   int                   pos,                /**< position of the variable in the constraint */
   int                   filterpos           /**< position of event filter entry returned by SCIPcatchVarEvent(), or -1 */
   )
{
   assert(consdata != NULL);
   assert(0 <= pos && pos < consdata->nvars);

   if( consdata->boundtypes[pos] == SCIP_BOUNDTYPE_LOWER )
   {
      SCIP_CALL( SCIPdropVarEvent(scip, consdata->vars[pos], SCIP_EVENTTYPE_UBTIGHTENED | SCIP_EVENTTYPE_LBRELAXED,
            eventhdlr, (SCIP_EVENTDATA*)cons, filterpos) );
   }
   else
   {
      SCIP_CALL( SCIPdropVarEvent(scip, consdata->vars[pos], SCIP_EVENTTYPE_LBTIGHTENED | SCIP_EVENTTYPE_UBRELAXED,
            eventhdlr, (SCIP_EVENTDATA*)cons, filterpos) );
   }

   return SCIP_OKAY;
}

/** creates constraint handler data for bound disjunction constraint handler */
static
SCIP_RETCODE conshdlrdataCreate(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONSHDLRDATA**   conshdlrdata,       /**< pointer to store the constraint handler data */
   SCIP_EVENTHDLR*       eventhdlr           /**< event handler */
   )
{
   assert(scip != NULL);
   assert(conshdlrdata != NULL);
   assert(eventhdlr != NULL);

   SCIP_CALL( SCIPallocBlockMemory(scip, conshdlrdata) );

   /* set event handler for catching events on watched variables */
   (*conshdlrdata)->eventhdlr = eventhdlr;

   return SCIP_OKAY;
}

/** frees constraint handler data for bound disjunction constraint handler */
static
SCIP_RETCODE conshdlrdataFree(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONSHDLRDATA**   conshdlrdata        /**< pointer to the constraint handler data */
   )
{
   assert(conshdlrdata != NULL);
   assert(*conshdlrdata != NULL);

   SCIPfreeBlockMemory(scip, conshdlrdata);

   return SCIP_OKAY;
}

/** creates a bound disjunction constraint data object */
static
SCIP_RETCODE consdataCreate(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONSDATA**       consdata,           /**< pointer to store the bound disjunction constraint data */
   int                   nvars,              /**< number of variables in the constraint */
   SCIP_VAR**            vars,               /**< variables of the literals in the constraint */
   SCIP_BOUNDTYPE*       boundtypes,         /**< types of bounds of the literals (lower or upper bounds) */
   SCIP_Real*            bounds              /**< bounds of the literals */
   )
{
   assert(consdata != NULL);
   assert(nvars == 0 || vars != NULL);
   assert(nvars == 0 || boundtypes != NULL);
   assert(nvars == 0 || bounds != NULL);

   SCIP_CALL( SCIPallocBlockMemory(scip, consdata) );

   if( nvars > 0 )
   {
      if( SCIPisConsCompressionEnabled(scip) )
      {
         int k;
         int v;
         int nviolations;
         SCIP_Bool redundant;
         SCIP_VAR** varsbuffer;
         SCIP_BOUNDTYPE* boundtypesbuffer;
         SCIP_Real* boundsbuffer;

         SCIP_CALL( SCIPallocBufferArray(scip, &varsbuffer, nvars) );
         SCIP_CALL( SCIPallocBufferArray(scip, &boundtypesbuffer, nvars) );
         SCIP_CALL( SCIPallocBufferArray(scip, &boundsbuffer, nvars) );

         nviolations = 0;
         k = 0;
         redundant = FALSE;
         /* loop over variables, compare fixed ones against its bound disjunction */
         for( v = 0; v < nvars && !redundant; ++v )
         {
            SCIP_VAR* var = vars[v];
            SCIP_BOUNDTYPE boundtype = boundtypes[v];
            SCIP_Real bound = bounds[v];

            /* is the variable fixed? */
            if( SCIPisEQ(scip, SCIPvarGetLbGlobal(var), SCIPvarGetUbGlobal(var)) )
            {
               if( (boundtype == SCIP_BOUNDTYPE_LOWER && isFeasGE(scip, var, SCIPvarGetLbLocal(var), bound))
               || (boundtype == SCIP_BOUNDTYPE_UPPER && isFeasLE(scip, var, SCIPvarGetUbLocal(var), bound)) )
               {
                  /* safe this feasible assignment at the first position */
                  varsbuffer[0] = var;
                  boundtypesbuffer[0] = boundtype;
                  boundsbuffer[0] = bound;
                  k = 1;
                  redundant = TRUE;
               }
               else
                  ++nviolations;
            }
            else
            {
               /* append unfixed variable to buffer */
               varsbuffer[k] = var;
               boundtypesbuffer[k] = boundtype;
               boundsbuffer[k] = bound;
               ++k;
            }
         }

         /* duplicate a single, infeasible assignment, wlog the first one */
         if( k == 0 )
         {
            assert(nviolations == nvars);
            SCIP_CALL( SCIPduplicateBlockMemoryArray(scip, &(*consdata)->vars, vars, 1) );
            SCIP_CALL( SCIPduplicateBlockMemoryArray(scip, &(*consdata)->boundtypes, boundtypes, 1) );
            SCIP_CALL( SCIPduplicateBlockMemoryArray(scip, &(*consdata)->bounds, bounds, 1) );
            (*consdata)->varssize = 1;
            (*consdata)->nvars = 1;
         }
         else
         {
            /* if the bound disjunction is already trivially satisfied, we keep only a single feasible assignment */
            assert(!redundant || k == 1);

            /* we only copy the buffered variables required to represent the constraint */
            SCIP_CALL( SCIPduplicateBlockMemoryArray(scip, &(*consdata)->vars, varsbuffer, k) );
            SCIP_CALL( SCIPduplicateBlockMemoryArray(scip, &(*consdata)->boundtypes, boundtypesbuffer, k) );
            SCIP_CALL( SCIPduplicateBlockMemoryArray(scip, &(*consdata)->bounds, boundsbuffer, k) );
            (*consdata)->varssize = k;
            (*consdata)->nvars = k;
         }

         /* free buffer storage */
         SCIPfreeBufferArray(scip, &boundsbuffer);
         SCIPfreeBufferArray(scip, &boundtypesbuffer);
         SCIPfreeBufferArray(scip, &varsbuffer);
      }
      else
      {
         /* without problem compression, the entire vars array is copied */
         SCIP_CALL( SCIPduplicateBlockMemoryArray(scip, &(*consdata)->vars, vars, nvars) );
         SCIP_CALL( SCIPduplicateBlockMemoryArray(scip, &(*consdata)->boundtypes, boundtypes, nvars) );
         SCIP_CALL( SCIPduplicateBlockMemoryArray(scip, &(*consdata)->bounds, bounds, nvars) );
         (*consdata)->varssize = nvars;
         (*consdata)->nvars = nvars;
      }
   }
   else
   {
      (*consdata)->vars = NULL;
      (*consdata)->boundtypes = NULL;
      (*consdata)->bounds = NULL;
      (*consdata)->varssize = 0;
      (*consdata)->nvars = 0;
   }
   (*consdata)->watchedvar1 = -1;
   (*consdata)->watchedvar2 = -1;
   (*consdata)->filterpos1 = -1;
   (*consdata)->filterpos2 = -1;

   /* get transformed variables, if we are in the transformed problem */
   if( SCIPisTransformed(scip) )
   {
      SCIP_CALL( SCIPgetTransformedVars(scip, (*consdata)->nvars, (*consdata)->vars, (*consdata)->vars) );
   }

   return SCIP_OKAY;
}   

/** frees a bound disjunction constraint data */
static
SCIP_RETCODE consdataFree(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONSDATA**       consdata            /**< pointer to the bound disjunction constraint */
   )
{
   assert(consdata != NULL);
   assert(*consdata != NULL);

   SCIPfreeBlockMemoryArrayNull(scip, &(*consdata)->vars, (*consdata)->varssize);
   SCIPfreeBlockMemoryArrayNull(scip, &(*consdata)->boundtypes, (*consdata)->varssize);
   SCIPfreeBlockMemoryArrayNull(scip, &(*consdata)->bounds, (*consdata)->varssize);
   SCIPfreeBlockMemory(scip, consdata);

   return SCIP_OKAY;
}

/** prints bound disjunction constraint to file stream */
static
void consdataPrint(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONSDATA*        consdata,           /**< bound disjunction constraint data */
   FILE*                 file,               /**< output file (or NULL for standard output) */
   SCIP_Bool             endline             /**< should an endline be set? */
   )
{
   int v;

   assert(consdata != NULL);

   /* print coefficients */
   SCIPinfoMessage(scip, file, "bounddisjunction(");
   for( v = 0; v < consdata->nvars; ++v )
   {
      assert(consdata->vars[v] != NULL);
      if( v > 0 )
         SCIPinfoMessage(scip, file, ", ");
      SCIPinfoMessage(scip, file, "<%s> %s %.15g", SCIPvarGetName(consdata->vars[v]),
         consdata->boundtypes[v] == SCIP_BOUNDTYPE_LOWER ? ">=" : "<=", consdata->bounds[v]);
   }
   SCIPinfoMessage(scip, file, ")");

   if( endline )
      SCIPinfoMessage(scip, file, "\n");
}

/** stores the given variable numbers as watched variables, and updates the event processing */
static
SCIP_RETCODE switchWatchedvars(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint */
   SCIP_EVENTHDLR*       eventhdlr,          /**< event handler to call for the event processing */
   int                   watchedvar1,        /**< new first watched variable */
   int                   watchedvar2         /**< new second watched variable */
   )
{
   SCIP_CONSDATA* consdata;

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);
   assert(watchedvar1 == -1 || watchedvar1 != watchedvar2);
   assert(watchedvar1 != -1 || watchedvar2 == -1);
   assert(watchedvar1 == -1 || (0 <= watchedvar1 && watchedvar1 < consdata->nvars));
   assert(watchedvar2 == -1 || (0 <= watchedvar2 && watchedvar2 < consdata->nvars));

   /* don't watch variables for non active constraints */
   if( !SCIPconsIsActive(cons) )
      return SCIP_OKAY;

   /* if one watched variable is equal to the old other watched variable, just switch positions */
   if( watchedvar1 == consdata->watchedvar2 || watchedvar2 == consdata->watchedvar1 )
   {
      int tmp;

      tmp = consdata->watchedvar1;
      consdata->watchedvar1 = consdata->watchedvar2;
      consdata->watchedvar2 = tmp;
      tmp = consdata->filterpos1;
      consdata->filterpos1 = consdata->filterpos2;
      consdata->filterpos2 = tmp;
   }
   assert(watchedvar1 == -1 || watchedvar1 != consdata->watchedvar2);
   assert(watchedvar2 == -1 || watchedvar2 != consdata->watchedvar1);

   /* drop events on old watched variables */
   if( consdata->watchedvar1 != -1 && consdata->watchedvar1 != watchedvar1 )
   {
      assert(consdata->filterpos1 != -1);
      SCIP_CALL( dropEvents(scip, cons, consdata, eventhdlr, consdata->watchedvar1, consdata->filterpos1) );
      consdata->watchedvar1 = -1;
   }
   if( consdata->watchedvar2 != -1 && consdata->watchedvar2 != watchedvar2 )
   {
      assert(consdata->filterpos2 != -1);
      SCIP_CALL( dropEvents(scip, cons, consdata, eventhdlr, consdata->watchedvar2, consdata->filterpos2) );
      consdata->watchedvar2 = -1;
   }

   /* catch events on new watched variables */
   if( watchedvar1 != -1 && watchedvar1 != consdata->watchedvar1 )
   {
      SCIP_CALL( catchEvents(scip, cons, consdata, eventhdlr, watchedvar1, &consdata->filterpos1) );
   }
   if( watchedvar2 != -1 && watchedvar2 != consdata->watchedvar2 )
   {
      SCIP_CALL( catchEvents(scip, cons, consdata, eventhdlr, watchedvar2, &consdata->filterpos2) );
   }

   /* set the new watched variables */
   consdata->watchedvar1 = watchedvar1;
   consdata->watchedvar2 = watchedvar2;

   return SCIP_OKAY;
}

/** check whether two intervals overlap */
static
SCIP_Bool isOverlapping(
   SCIP*                 scip,
   SCIP_VAR*             var,
   SCIP_BOUNDTYPE        boundtype1,
   SCIP_Real             bound1,
   SCIP_BOUNDTYPE        boundtype2,
   SCIP_Real             bound2
   )
{
   SCIP_Bool overlapping = FALSE;

   if( boundtype1 == SCIP_BOUNDTYPE_LOWER )
   {
      assert(boundtype2 == SCIP_BOUNDTYPE_UPPER);

      if( SCIPisLE(scip, bound1 - bound2, (SCIP_Real)SCIPvarIsIntegral(var)) )
         overlapping = TRUE;
   }
   else
   {
      assert(boundtype2 == SCIP_BOUNDTYPE_LOWER);

      if( SCIPisLE(scip, bound2 - bound1, (SCIP_Real)SCIPvarIsIntegral(var)) )
         overlapping = TRUE;
   }

   return overlapping;
}

/** deletes coefficient at given position from bound disjunction constraint data */
static
SCIP_RETCODE delCoefPos(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint */
   SCIP_EVENTHDLR*       eventhdlr,          /**< event handler to call for the event processing */
   int                   pos                 /**< position of coefficient to delete */
   )
{
   SCIP_CONSDATA* consdata;

   assert(eventhdlr != NULL);

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);
   assert(0 <= pos && pos < consdata->nvars);
   assert(SCIPconsIsTransformed(cons) == SCIPvarIsTransformed(consdata->vars[pos]));

   /* remove the rounding locks of variable */
   SCIP_CALL( unlockRounding(scip, cons, consdata, pos) );

   if( SCIPconsIsTransformed(cons) )
   {
      /* if the position is watched, stop watching the position */
      if( consdata->watchedvar1 == pos )
      {
         SCIP_CALL( switchWatchedvars(scip, cons, eventhdlr, consdata->watchedvar2, -1) );
      }
      if( consdata->watchedvar2 == pos )
      {
         SCIP_CALL( switchWatchedvars(scip, cons, eventhdlr, consdata->watchedvar1, -1) );
      }
   }
   assert(pos != consdata->watchedvar1);
   assert(pos != consdata->watchedvar2);

   /* move the last variable to the free slot */
   consdata->vars[pos] = consdata->vars[consdata->nvars-1];
   consdata->boundtypes[pos] = consdata->boundtypes[consdata->nvars-1];
   consdata->bounds[pos] = consdata->bounds[consdata->nvars-1];
   consdata->nvars--;

   /* if the last variable (that moved) was watched, update the watched position */
   if( consdata->watchedvar1 == consdata->nvars )
      consdata->watchedvar1 = pos;
   if( consdata->watchedvar2 == consdata->nvars )
      consdata->watchedvar2 = pos;

   SCIP_CALL( SCIPenableConsPropagation(scip, cons) );

   return SCIP_OKAY;
}

/** adds literal to bound disjunction constraint data */
static
SCIP_RETCODE addCoef(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint */
   SCIP_EVENTHDLR*       eventhdlr,          /**< event handler to call for the event processing */
   SCIP_VAR*             var,                /**< variable in literal */
   SCIP_BOUNDTYPE        boundtype,          /**< boundtype of literal */
   SCIP_Real             bound,              /**< bound of literal */
   SCIP_Bool*            redundant           /**< flag to indicate whether constraint has been bound redundant */
   )
{
   SCIP_CONSDATA* consdata;
   int samebndidx;
   int v;

   assert(eventhdlr != NULL);

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);
   assert(var != NULL);
   assert(!SCIPisInfinity(scip, REALABS(bound)));
   assert(SCIPconsIsTransformed(cons) == SCIPvarIsTransformed(var));

   /* ensure enough memory in consdata arrays */
   if( consdata->varssize == consdata->nvars )
   {
      int newsize;

      newsize = SCIPcalcMemGrowSize(scip, consdata->nvars + 1);
      SCIP_CALL( SCIPreallocBlockMemoryArray(scip, &consdata->vars,       consdata->varssize, newsize) );
      SCIP_CALL( SCIPreallocBlockMemoryArray(scip, &consdata->boundtypes, consdata->varssize, newsize) );
      SCIP_CALL( SCIPreallocBlockMemoryArray(scip, &consdata->bounds,     consdata->varssize, newsize) );
      consdata->varssize = newsize;
   }
   assert(consdata->varssize > consdata->nvars);

   /* remember the position of the literal in the constraint that has the same bound type on the same variable
    *
    * example: (x >= 5) or (x <= 2) and literal (x >= 2) should be added.
    *          if we see (x >= 5) first, we cannot stop immediately because only in combination with the second literal
    *          we see that the constraint is redundant.
    */
   samebndidx = -1;

   for( v = 0; v < consdata->nvars; v++ )
   {
      /* check if the variable is already part of the constraint */
      if( consdata->vars[v] == var )
      {
         if( consdata->boundtypes[v] == boundtype )
            samebndidx = v;
         else if( isOverlapping(scip, var, consdata->boundtypes[v], consdata->bounds[v], boundtype, bound) )
         {
            *redundant = TRUE;
            return SCIP_OKAY;
         }
      }
   }

   /* the combination of variable and boundtype is already part of the constraint; check whether the clause
    * can be relaxed
    */
   if( samebndidx > -1 )
   {
      if( (boundtype == SCIP_BOUNDTYPE_LOWER && SCIPisLT(scip, bound, consdata->bounds[samebndidx]))
         || (boundtype == SCIP_BOUNDTYPE_UPPER && SCIPisGT(scip, bound, consdata->bounds[samebndidx])) )
      {
         SCIPdebugMsg(scip, "relax clause of <%s>: (<%s> %s %.15g) -> (<%s> %s %.15g)\n", SCIPconsGetName(cons),
               SCIPvarGetName(var), boundtype == SCIP_BOUNDTYPE_LOWER ? ">=" : "<=", consdata->bounds[samebndidx],
               SCIPvarGetName(var), boundtype == SCIP_BOUNDTYPE_LOWER ? ">=" : "<=", bound);
         consdata->bounds[samebndidx] = bound;
      }
   }
   else
   {
      /* add the variable to the end of the array */
      consdata->vars[consdata->nvars] = var;
      consdata->boundtypes[consdata->nvars] = boundtype;
      consdata->bounds[consdata->nvars] = bound;
      consdata->nvars++;

      if( SCIPconsIsTransformed(cons) )
      {
         /* add rounding lock of variable */
         SCIP_CALL( lockRounding(scip, cons, consdata, consdata->nvars-1) );

         /* if less than 2 variables are watched, add the new one to the watched variables */
         if( consdata->watchedvar1 == -1 )
         {
            assert(consdata->watchedvar2 == -1);
            SCIP_CALL( switchWatchedvars(scip, cons, eventhdlr, consdata->nvars-1, -1) );
         }
         else if( consdata->watchedvar2 == -1 )
         {
            SCIP_CALL( switchWatchedvars(scip, cons, eventhdlr, consdata->watchedvar1, consdata->nvars-1) );
         }
      }
   }

   SCIP_CALL( SCIPenableConsPropagation(scip, cons) );

   return SCIP_OKAY;
}

/** deletes all variables with global bounds violating the literal, checks for global bounds satisfying the literal */
static
SCIP_RETCODE applyGlobalBounds(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint */
   SCIP_EVENTHDLR*       eventhdlr,          /**< event handler to call for the event processing */
   SCIP_Bool*            redundant           /**< returns whether a variable fixed to one exists in the constraint */
   )
{
   SCIP_CONSDATA* consdata;
   int v;
   SCIP_Real bnd;

   assert(eventhdlr != NULL);
   assert(redundant != NULL);

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);
   assert(consdata->nvars == 0 || consdata->vars != NULL);

   *redundant = FALSE;
   v = 0;
   while( v < consdata->nvars )
   {
      SCIP_VAR* var;

      var = consdata->vars[v];

      if( consdata->boundtypes[v] == SCIP_BOUNDTYPE_LOWER )
      {
         bnd = SCIPcomputeVarLbGlobal(scip, var);
         if( isFeasGE(scip, var, bnd, consdata->bounds[v]) )
         {
            *redundant = TRUE;
            return SCIP_OKAY;
         }
         else
         {
            bnd = SCIPcomputeVarUbGlobal(scip, var);
            if( isFeasLT(scip, var, bnd, consdata->bounds[v]) )
            {
               SCIP_CALL( delCoefPos(scip, cons, eventhdlr, v) );
            }
            else
               ++v;
         }
      }
      else
      {
         assert(consdata->boundtypes[v] == SCIP_BOUNDTYPE_UPPER);
         bnd = SCIPcomputeVarUbGlobal(scip, var);
         if( isFeasLE(scip, var, bnd, consdata->bounds[v]) )
         {
            *redundant = TRUE;
            return SCIP_OKAY;
         }
         else
         {
            bnd = SCIPcomputeVarLbGlobal(scip, var);
            if( isFeasGT(scip, var, bnd, consdata->bounds[v]) )
            {
               SCIP_CALL( delCoefPos(scip, cons, eventhdlr, v) );
            }
            else
               ++v;
         }
      }
   }

   SCIPdebugMsg(scip, "after global bounds: ");
   SCIPdebug(consdataPrint(scip, consdata, NULL, TRUE));

   return SCIP_OKAY;
}

/** returns whether literal at the given position is satisfied in the local bounds */
static
SCIP_Bool isLiteralSatisfied(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONSDATA*        consdata,           /**< bound disjunction constraint data */
   int                   pos                 /**< position of the literal */
   )
{
   SCIP_Real bnd;

   assert(consdata != NULL);
   assert(0 <= pos && pos < consdata->nvars);

   if( consdata->boundtypes[pos] == SCIP_BOUNDTYPE_LOWER )
   {
      bnd = SCIPcomputeVarLbLocal(scip, consdata->vars[pos]);
      return isFeasGE(scip, consdata->vars[pos], bnd, consdata->bounds[pos]);
   }
   else
   {
      bnd = SCIPcomputeVarUbLocal(scip, consdata->vars[pos]);
      return isFeasLE(scip, consdata->vars[pos], bnd, consdata->bounds[pos]);
   }
}

/** returns whether literal at the given position is violated in the local bounds */
static
SCIP_Bool isLiteralViolated(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONSDATA*        consdata,           /**< bound disjunction constraint data */
   int                   pos                 /**< position of the literal */
   )
{
   SCIP_Real bnd;

   assert(consdata != NULL);
   assert(0 <= pos && pos < consdata->nvars);

   if( consdata->boundtypes[pos] == SCIP_BOUNDTYPE_LOWER )
   {
      bnd = SCIPcomputeVarUbLocal(scip, consdata->vars[pos]);
      return isFeasLT(scip, consdata->vars[pos], bnd, consdata->bounds[pos]);
   }
   else
   {
      bnd = SCIPcomputeVarLbLocal(scip, consdata->vars[pos]);
      return isFeasGT(scip, consdata->vars[pos], bnd, consdata->bounds[pos]);
   }
}

/** replace variables by their representative active (or multi-aggregated) variables */
static
SCIP_RETCODE removeFixedVariables(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint */
   SCIP_EVENTHDLR*       eventhdlr,          /**< event handler */
   SCIP_Bool*            redundant           /**< flag to indicate whether constraint has been bound redundant */
   )
{
   SCIP_CONSDATA* consdata;
   SCIP_VAR* var;
   SCIP_BOUNDTYPE boundtype;
   SCIP_Real bound;
   int v;

   assert(scip != NULL);
   assert(cons != NULL);
   assert(eventhdlr != NULL);

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   v = 0;
   while( v < consdata->nvars )
   {
#ifndef NDEBUG
      SCIP_VAR* oldvar;
#endif
      var = consdata->vars[v];
      assert(var != NULL);

#ifndef NDEBUG
      oldvar = var;
#endif

      if( SCIPvarIsActive(var) || SCIPvarGetStatus(var) == SCIP_VARSTATUS_MULTAGGR )
      {
         /* check whether the literal is satisfied and the constraint is thus redundant */
         if( isLiteralSatisfied(scip, consdata, v) )
         {
            *redundant = TRUE;
            break;
         }

         ++v;
         continue;
      }

      /* get active/fixed/multiaggr equivalent of v'th literal */
      bound = consdata->bounds[v];
      boundtype = consdata->boundtypes[v];
      SCIP_CALL( SCIPvarGetProbvarBound(&var, &bound, &boundtype) );
      assert(SCIPvarGetStatus(var) == SCIP_VARSTATUS_FIXED || oldvar != var);

      SCIPdebugMsg(scip, "in <%s>, replace <%s>[%g,%g] %c= %g by <%s>[%g,%g] %c= %g\n", SCIPconsGetName(cons),
         SCIPvarGetName(consdata->vars[v]), SCIPvarGetLbGlobal(consdata->vars[v]), SCIPvarGetUbGlobal(consdata->vars[v]), (consdata->boundtypes[v] == SCIP_BOUNDTYPE_LOWER ? '>' : '<'), consdata->bounds[v],
         SCIPvarGetName(var), SCIPvarGetLbGlobal(var), SCIPvarGetUbGlobal(var), (boundtype == SCIP_BOUNDTYPE_LOWER ? '>' : '<'), bound);

      /* if literal is satisfied, then constraint is redundant and we can stop */
      if( (boundtype == SCIP_BOUNDTYPE_LOWER && isFeasLE(scip, var, bound, SCIPvarGetLbGlobal(var))) || /*lint !e666*/
         (boundtype == SCIP_BOUNDTYPE_UPPER && isFeasGE(scip, var, bound, SCIPvarGetUbGlobal(var))) ) /*lint !e666*/
      {
          *redundant = TRUE;
          break;
      }

      /* if literal is not fixed, replace it */
      if( SCIPvarGetStatus(var) != SCIP_VARSTATUS_FIXED )
      {
         /* add new literal */
         SCIP_CALL( addCoef(scip, cons, eventhdlr, var, boundtype, bound, redundant) );
      }

      /* remove old literal */
      SCIP_CALL( delCoefPos(scip, cons, eventhdlr, v) );
   }

   return SCIP_OKAY;
}

/** try to upgrade the bounddisjunction constraint
 *
 *  if only binary variables are left, we can upgrade a bounddisjunction to a logicor constraint(, if only two variables
 *  are left, this logicor constraint can be formulated as set-packing constraint as well)
 *
 *  e.g.: bounddisjunction( x1 >= 1, x2 <= 0; x3 >= 1; x4 <= 0 )   =>   x1 + ~x2 + x3 + ~x4 >= 1
 */
static
SCIP_RETCODE upgradeCons(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint that detected the conflict */
   int*                  ndelconss,          /**< pointer to store the number of delete constraint */
   int*                  naddconss           /**< pointer to store the number of added constraint */
   )
{
   SCIP_CONSDATA* consdata;
   SCIP_VAR** newvars;
   SCIP_Bool allbinary;
   int nvars;
   int v;

   assert(scip != NULL);
   assert(cons != NULL);
   assert(ndelconss != NULL);
   assert(naddconss != NULL);
   assert(naddconss != NULL);
   assert(!SCIPconsIsModifiable(cons));

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   nvars = consdata->nvars;
   assert(nvars >= 2);
   assert(consdata->vars != NULL);

   allbinary = TRUE;

   SCIP_CALL( SCIPallocBufferArray(scip, &newvars, nvars) );

   for( v = nvars - 1; v >= 0; --v )
   {
      if( !SCIPvarIsBinary(consdata->vars[v]) )
      {
         allbinary = FALSE;
         break;
      }
      else
      {
         if( consdata->boundtypes[v] == SCIP_BOUNDTYPE_LOWER )
         {
            assert(SCIPisFeasGT(scip, consdata->bounds[v], 0.0));

            if( nvars == 2 )
            {
               SCIP_CALL( SCIPgetNegatedVar(scip, consdata->vars[v], &(newvars[v])) );
            }
            else
               newvars[v] = consdata->vars[v];
         }
         else
         {
            assert(consdata->boundtypes[v] == SCIP_BOUNDTYPE_UPPER);
            assert(SCIPisFeasLT(scip, consdata->bounds[v], 1.0));

            if( nvars > 2 )
            {
               SCIP_CALL( SCIPgetNegatedVar(scip, consdata->vars[v], &(newvars[v])) );
            }
            else
               newvars[v] = consdata->vars[v];
         }
      }
   }

   if( allbinary )
   {
      SCIP_CONS* newcons;

      if( nvars == 2 )
      {
         SCIP_CALL( SCIPcreateConsSetpack(scip, &newcons, SCIPconsGetName(cons), nvars, newvars,
               SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
               SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),
               SCIPconsIsLocal(cons), SCIPconsIsModifiable(cons),
               SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons), SCIPconsIsStickingAtNode(cons)) );
      }
      else
      {
         SCIP_CALL( SCIPcreateConsLogicor(scip, &newcons, SCIPconsGetName(cons), nvars, newvars,
               SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
               SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),
               SCIPconsIsLocal(cons), SCIPconsIsModifiable(cons),
               SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons), SCIPconsIsStickingAtNode(cons)) );
      }

      SCIPdebugMsg(scip, "updated constraint <%s> to the following %s constraint\n", SCIPconsGetName(cons), (nvars == 2 ? "setppc" : "logicor"));
      SCIPdebugPrintCons(scip, newcons, NULL);
      SCIP_CALL( SCIPaddCons(scip, newcons) );
      SCIP_CALL( SCIPreleaseCons(scip, &newcons) );
      ++(*naddconss);

      SCIP_CALL( SCIPdelCons(scip, cons) );
      ++(*ndelconss);
   }

   SCIPfreeBufferArray(scip, &newvars);

   return SCIP_OKAY;
}

/** analyzes conflicting assignment on given constraint, and adds conflict constraint to problem */
static
SCIP_RETCODE analyzeConflict(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< bound disjunction constraint that detected the conflict */
   )
{
   SCIP_CONSDATA* consdata;
   int v;

   /* conflict analysis can only be applied in solving stage and if it is turned on */
   if( (SCIPgetStage(scip) != SCIP_STAGE_SOLVING && !SCIPinProbing(scip)) || !SCIPisConflictAnalysisApplicable(scip) )
      return SCIP_OKAY;

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   /* initialize conflict analysis, and add all bounds of infeasible constraint to conflict candidate queue */
   SCIP_CALL( SCIPinitConflictAnalysis(scip, SCIP_CONFTYPE_PROPAGATION, FALSE) );

   for( v = 0; v < consdata->nvars; ++v )
   {
      /* the opposite bound is in conflict with this literal */
      SCIP_CALL( SCIPaddConflictBd(scip, consdata->vars[v], SCIPboundtypeOpposite(consdata->boundtypes[v]), NULL) );
   }

   /* analyze the conflict */
   SCIP_CALL( SCIPanalyzeConflictCons(scip, cons, NULL) );

   return SCIP_OKAY;
}

/** disables or deletes the given constraint, depending on the current depth */
static
SCIP_RETCODE disableCons(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< bound disjunction constraint to be disabled */
   )
{
   assert(SCIPconsGetValidDepth(cons) <= SCIPgetDepth(scip));

   if( SCIPgetDepth(scip) == SCIPconsGetValidDepth(cons) )
   {
      SCIP_CALL( SCIPdelCons(scip, cons) );
   }
   else
   {
      SCIP_CALL( SCIPdisableCons(scip, cons) );
   }

   return SCIP_OKAY;
}

/** checks constraint for violation only looking at the watched variables, applies bound changes if possible */
static
SCIP_RETCODE processWatchedVars(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint to be processed */
   SCIP_EVENTHDLR*       eventhdlr,          /**< event handler to call for the event processing */
   SCIP_Bool*            cutoff,             /**< pointer to store TRUE, if the node can be cut off */
   SCIP_Bool*            infeasible,         /**< pointer to store TRUE, if the constraint is infeasible in current bounds */
   SCIP_Bool*            reduceddom,         /**< pointer to store TRUE, if a domain reduction was found */
   SCIP_Bool*            mustcheck           /**< pointer to store whether this constraint must be checked for feasibility */
   )
{
   SCIP_CONSDATA* consdata;
   SCIP_VAR** vars;
   SCIP_BOUNDTYPE* boundtypes;
   SCIP_Real* bounds;
   SCIP_Longint nbranchings1;
   SCIP_Longint nbranchings2;
   int nvars;
   int watchedvar1;
   int watchedvar2;

   assert(cons != NULL);
   assert(SCIPconsGetHdlr(cons) != NULL);
   assert(strcmp(SCIPconshdlrGetName(SCIPconsGetHdlr(cons)), CONSHDLR_NAME) == 0);
   assert(cutoff != NULL);
   assert(reduceddom != NULL);
   assert(mustcheck != NULL);

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);
   assert(consdata->watchedvar1 == -1 || consdata->watchedvar1 != consdata->watchedvar2);

   /* init bools */
   *cutoff = FALSE;
   *infeasible = FALSE;
   *reduceddom = FALSE;
   *mustcheck = FALSE;

   SCIPdebugMsg(scip, "processing watched variables of constraint <%s>\n", SCIPconsGetName(cons));

   nvars = consdata->nvars;
   vars = consdata->vars;
   boundtypes = consdata->boundtypes;
   bounds = consdata->bounds;
   assert(nvars == 0 || vars != NULL);
   assert(nvars == 0 || boundtypes != NULL);
   assert(nvars == 0 || bounds != NULL);

   /* check watched variables if they are satisfying the literal */
   if( consdata->watchedvar1 >= 0 && isLiteralSatisfied(scip, consdata, consdata->watchedvar1) )
   {
      /* the literal is satisfied, making the constraint redundant */
      SCIPdebugMsg(scip, " -> disabling constraint <%s> (watchedvar1 satisfied)\n", SCIPconsGetName(cons));
      SCIP_CALL( disableCons(scip, cons) );
      return SCIP_OKAY;
   }
   if( consdata->watchedvar2 >= 0 && isLiteralSatisfied(scip, consdata, consdata->watchedvar2) )
   {
      /* the literal is satisfied, making the constraint redundant */
      SCIPdebugMsg(scip, " -> disabling constraint <%s> (watchedvar2 satisfied)\n", SCIPconsGetName(cons));
      SCIP_CALL( disableCons(scip, cons) );
      return SCIP_OKAY;
   }

   /* check if watched variables are still undecided */
   watchedvar1 = -1;
   watchedvar2 = -1;
   nbranchings1 = SCIP_LONGINT_MAX;
   nbranchings2 = SCIP_LONGINT_MAX;
   if( consdata->watchedvar1 >= 0 && !isLiteralViolated(scip, consdata, consdata->watchedvar1) )
   {
      watchedvar1 = consdata->watchedvar1;
      nbranchings1 = -1; /* prefer keeping the watched variable */
   }
   if( consdata->watchedvar2 >= 0 && !isLiteralViolated(scip, consdata, consdata->watchedvar2) )
   {
      if( watchedvar1 == -1 )
      {
         watchedvar1 = consdata->watchedvar2;
         nbranchings1 = -1; /* prefer keeping the watched variable */
      }
      else
      {
         watchedvar2 = consdata->watchedvar2;
         nbranchings2 = -1; /* prefer keeping the watched variable */
      }
   }
   assert(watchedvar1 >= 0 || watchedvar2 == -1);
   assert(nbranchings1 <= nbranchings2);
   assert(watchedvar1 != -1 || nbranchings1 == SCIP_LONGINT_MAX);
   assert(watchedvar2 != -1 || nbranchings2 == SCIP_LONGINT_MAX);

   /* search for new watched variables */
   if( watchedvar2 == -1 )
   {
      int v;

      for( v = 0; v < nvars; ++v )
      {
         SCIP_Longint nbranchings;

         /* don't process the watched variables again */
         if( v == consdata->watchedvar1 || v == consdata->watchedvar2 )
            continue;

         /* check, if the literal is violated */
         if( isLiteralViolated(scip, consdata, v) )
            continue;

         /* check, if the literal is satisfied */
         if( isLiteralSatisfied(scip, consdata, v) )
         {
            assert(v != consdata->watchedvar1);
            assert(v != consdata->watchedvar2);

            /* the literal is satisfied, making the constraint redundant;
             * make sure, the feasible variable is watched and disable the constraint
             */
            SCIPdebugMsg(scip, " -> disabling constraint <%s> (variable <%s> fixed to 1.0)\n",
               SCIPconsGetName(cons), SCIPvarGetName(vars[v]));
            if( consdata->watchedvar1 != -1 )
            {
               SCIP_CALL( switchWatchedvars(scip, cons, eventhdlr, consdata->watchedvar1, v) );
            }
            else
            {
               SCIP_CALL( switchWatchedvars(scip, cons, eventhdlr, v, consdata->watchedvar2) );
            }
            SCIP_CALL( disableCons(scip, cons) );
            return SCIP_OKAY;
         }

         /* the literal is still undecided and can be used as watched variable */
         nbranchings = SCIPvarGetNBranchingsCurrentRun(vars[v], 
            boundtypes[v] == SCIP_BOUNDTYPE_LOWER ? SCIP_BRANCHDIR_DOWNWARDS : SCIP_BRANCHDIR_UPWARDS);
         if( nbranchings < nbranchings2 )
         {
            if( nbranchings < nbranchings1 )
            {
               watchedvar2 = watchedvar1;
               nbranchings2 = nbranchings1;
               watchedvar1 = v;
               nbranchings1 = nbranchings;
            }
            else
            {
               watchedvar2 = v;
               nbranchings2 = nbranchings;
            }
         }
      }
   }
   assert(nbranchings1 <= nbranchings2);
   assert(watchedvar1 >= 0 || watchedvar2 == -1);

   if( watchedvar1 == -1 )
   {
      /* there is no undecided literal left -> the constraint is infeasible
       *  - a modifiable constraint is infeasible
       *  - an unmodifiable constraint is infeasible and the node can be cut off
       */
      assert(watchedvar2 == -1);

      SCIPdebugMsg(scip, " -> constraint <%s> is infeasible\n", SCIPconsGetName(cons));
      *infeasible = TRUE;

      SCIP_CALL( SCIPresetConsAge(scip, cons) );
      if( !SCIPconsIsModifiable(cons) )
      {
         /* use conflict analysis to get a conflict constraint out of the conflicting assignment */
         SCIP_CALL( analyzeConflict(scip, cons) );

         /* mark the node to be cut off */
         *cutoff = TRUE;
      }
   }
   else if( watchedvar2 == -1 )
   {
      /* there is only one undecided literal:
       * - a modifiable constraint must be checked manually
       * - we cannot change bounds of multi-aggregated variables and have to check manually
       * - an unmodifiable constraint is feasible and can be disabled after the remaining literal is satisfied
       */
      assert(0 <= watchedvar1 && watchedvar1 < nvars);
      assert(!isLiteralViolated(scip, consdata, watchedvar1));
      assert(!isLiteralSatisfied(scip, consdata, watchedvar1));
      if( SCIPconsIsModifiable(cons)
         || SCIPvarGetStatus(SCIPvarGetProbvar(vars[watchedvar1])) == SCIP_VARSTATUS_MULTAGGR )
         *mustcheck = TRUE;
      else
      {
         SCIP_Bool infbdchg;

#ifndef NDEBUG
         int v;

         /* check whether all other literals are violated */
         for (v = 0; v < nvars; ++v)
         {
            if ( v != watchedvar1 )
            {
               assert( isLiteralViolated(scip, consdata, v) );
            }
         }
#endif

         /* satisfy remaining literal and disable constraint; make sure, the fixed-to-one variable is watched */
         SCIPdebugMsg(scip, " -> single-literal constraint <%s> (change bound <%s> %s %g) at depth %d\n",
            SCIPconsGetName(cons), SCIPvarGetName(vars[watchedvar1]),
            boundtypes[watchedvar1] == SCIP_BOUNDTYPE_LOWER ? ">=" : "<=", bounds[watchedvar1], SCIPgetDepth(scip));

         if( boundtypes[watchedvar1] == SCIP_BOUNDTYPE_LOWER )
         {
            SCIP_CALL( SCIPinferVarLbCons(scip, vars[watchedvar1], bounds[watchedvar1], cons, watchedvar1, TRUE,
                  &infbdchg, NULL) );
         }
         else
         {
            SCIP_CALL( SCIPinferVarUbCons(scip, vars[watchedvar1], bounds[watchedvar1], cons, watchedvar1, TRUE,
                  &infbdchg, NULL) );
         }
         assert(!infbdchg);
         SCIP_CALL( SCIPresetConsAge(scip, cons) );
         if( watchedvar1 != consdata->watchedvar1 ) /* keep one of the watched variables */
         {
            SCIP_CALL( switchWatchedvars(scip, cons, eventhdlr, watchedvar1, consdata->watchedvar1) );
         }
         SCIP_CALL( disableCons(scip, cons) );
         *reduceddom = TRUE;
      }
   }
   else
   {
      SCIPdebugMsg(scip, " -> new watched variables <%s> and <%s> of constraint <%s> are still undecided\n",
         SCIPvarGetName(vars[watchedvar1]), SCIPvarGetName(vars[watchedvar2]), SCIPconsGetName(cons));

      /* switch to the new watched variables */
      SCIP_CALL( switchWatchedvars(scip, cons, eventhdlr, watchedvar1, watchedvar2) );

      /* there are at least two undecided variables -> the constraint must be checked manually */
      *mustcheck = TRUE;

      /* disable propagation of constraint until the corresponding bound of a watched variable changed */
      SCIP_CALL( SCIPdisableConsPropagation(scip, cons) );

      /* increase aging counter */
      SCIP_CALL( SCIPaddConsAge(scip, cons, AGEINCREASE(consdata->nvars)) );
   }

   return SCIP_OKAY;
}

/** checks constraint for violation, returns TRUE iff constraint is feasible */
static
SCIP_RETCODE checkCons(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint to be checked */
   SCIP_SOL*             sol,                /**< primal CIP solution */
   SCIP_Bool*            violated            /**< pointer to store whether the given solution violates the constraint */
   )
{
   SCIP_CONSDATA* consdata;
   SCIP_VAR** vars;
   SCIP_BOUNDTYPE* boundtypes;
   SCIP_Real* bounds;
   SCIP_Real solval;
   SCIP_Real viol;
   SCIP_Real absviol;
   int violpos;
   int nvars;
   int v;

   assert(violated != NULL);

   *violated = FALSE;
   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   nvars = consdata->nvars;
   vars = consdata->vars;
   boundtypes = consdata->boundtypes;
   bounds = consdata->bounds;
   assert(nvars == 0 || vars != NULL);
   assert(nvars == 0 || boundtypes != NULL);
   assert(nvars == 0 || bounds != NULL);

   /* check the given solution */
   absviol = SCIP_REAL_MAX;
   violpos = -1;
   *violated = TRUE;
   for( v = 0; v < nvars; ++v )
   {
      solval = SCIPgetSolVal(scip, sol, vars[v]);

      /* update absolute violation if needed */
      viol = (boundtypes[v] == SCIP_BOUNDTYPE_LOWER) ? bounds[v] - solval : solval - bounds[v];
      if( viol < absviol )
      {
         absviol = viol;
         violpos = v;
      }

      if( (boundtypes[v] == SCIP_BOUNDTYPE_LOWER && isFeasGE(scip, vars[v], solval, bounds[v]))
         || (boundtypes[v] == SCIP_BOUNDTYPE_UPPER && isFeasLE(scip, vars[v], solval, bounds[v])) )
      {
         *violated = FALSE;
         break;
      }
   }
   /* update constraint violation in solution */
   if( sol != NULL )
   {
      SCIP_Real relviol;

      assert(0 == nvars || -1 != violpos);

      if( 0 == nvars )
         relviol = SCIP_REAL_MAX;
      else
         relviol = SCIPrelDiff(SCIPgetSolVal(scip, sol, vars[violpos]), bounds[violpos]);

      SCIPupdateSolConsViolation(scip, sol, absviol, relviol);
   }
   return SCIP_OKAY;
}

/* registers variables of a constraint as branching candidates 
 * indicates whether an n-ary branch is necessary to enforce this constraint, 
 * because all active literals are w.r.t. continuous variables which bound (in the literal) is at the variable's bound 
 */
static
SCIP_RETCODE registerBranchingCandidates(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint which variables should be registered for branching */
   SCIP_SOL*             sol,                /**< solution (NULL for LP solution) */
   SCIP_Bool*            neednarybranch      /**< pointer to store TRUE, if n-ary branching is necessary to enforce this constraint */
   )
{
   SCIP_CONSDATA* consdata;
   SCIP_VAR** vars;
   SCIP_BOUNDTYPE* boundtypes;
   SCIP_Real* bounds;
   SCIP_Real violation;
   SCIP_Real varlb;
   SCIP_Real varub;
   int nvars;
   int v;

   assert(cons != NULL);
   assert(SCIPconsGetHdlr(cons) != NULL);
   assert(strcmp(SCIPconshdlrGetName(SCIPconsGetHdlr(cons)), CONSHDLR_NAME) == 0);
   assert(neednarybranch != NULL);

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);
   nvars = consdata->nvars;
   vars = consdata->vars;
   boundtypes = consdata->boundtypes;
   bounds = consdata->bounds;
   assert(nvars == 0 || vars != NULL);
   assert(nvars == 0 || boundtypes != NULL);
   assert(nvars == 0 || bounds != NULL);

   *neednarybranch = TRUE;

   for( v = 0; v < nvars; ++v )
   {
      SCIP_VAR* var;

      var = vars[v];
      assert(var != NULL);

      /* constraint should be violated, so all bounds in the constraint have to be violated */
      assert( !(boundtypes[v] == SCIP_BOUNDTYPE_LOWER && SCIPisFeasGE(scip, SCIPgetSolVal(scip, sol, var), bounds[v])) &&
         !(boundtypes[v] == SCIP_BOUNDTYPE_UPPER && SCIPisFeasLE(scip, SCIPgetSolVal(scip, sol, var), bounds[v])) );

      varlb = SCIPcomputeVarLbLocal(scip, var);
      varub = SCIPcomputeVarUbLocal(scip, var);

      /* if literal is x >= varlb, but upper bound on x is < varlb, then this literal can never be satisfied,
       * thus there is no use for branching
       */
      if( boundtypes[v] == SCIP_BOUNDTYPE_LOWER && isFeasLT(scip, var, varub, bounds[v]) )
         continue;

      /* if literal is x <= varub, but lower bound on x is > varub, then this literal can never be satisfied,
       * thus there is no use for branching
       */
      if( boundtypes[v] == SCIP_BOUNDTYPE_UPPER && isFeasGT(scip, var, varlb, bounds[v]) )
         continue;

      /* if literal is always satisfied, then no need to branch on it may happen if propagation is disabled for some
       * reason and due to numerics current solution does not satisfy literal, but variable bounds do
       */
      if( isLiteralSatisfied(scip, consdata, v) )
         continue;

      violation = SCIPgetSolVal(scip, sol, var) - bounds[v];

      /* if variable is continuous, then we cannot branch on one of the variable bounds */
      if( SCIPvarGetType(vars[v]) != SCIP_VARTYPE_CONTINUOUS ||
         ((SCIPisInfinity(scip, -varlb) || !SCIPisFeasEQ(scip, bounds[v], varlb)) &&
          (SCIPisInfinity(scip,  varub) || !SCIPisFeasEQ(scip, bounds[v], varub))) )
      {
         SCIP_CALL( SCIPaddExternBranchCand(scip, var, REALABS(violation), bounds[v]) );
         *neednarybranch = FALSE;
      }
   }

   return SCIP_OKAY;
}

/** enforces the pseudo or LP solution on the given constraint */
static
SCIP_RETCODE enforceCurrentSol(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint to be separated */
   SCIP_SOL*             sol,                /**< solution which should be enforced (NULL for LP solution) */
   SCIP_EVENTHDLR*       eventhdlr,          /**< event handler to call for the event processing */
   SCIP_Bool*            cutoff,             /**< pointer to store TRUE, if the node can be cut off */
   SCIP_Bool*            infeasible,         /**< pointer to store TRUE, if the constraint was infeasible */
   SCIP_Bool*            reduceddom,         /**< pointer to store TRUE, if a domain reduction was found */
   SCIP_Bool*            registeredbrcand    /**< pointer to store TRUE, if branching variable candidates were registered or was already true */
   )
{
   SCIP_Bool mustcheck;
   SCIP_Bool neednarybranch;

   assert(cons != NULL);
   assert(SCIPconsGetHdlr(cons) != NULL);
   assert(strcmp(SCIPconshdlrGetName(SCIPconsGetHdlr(cons)), CONSHDLR_NAME) == 0);
   assert(cutoff != NULL);
   assert(infeasible != NULL);
   assert(reduceddom != NULL);
   assert(registeredbrcand != NULL);

   SCIPdebugMsg(scip, "enforce bound disjunction constraint <%s>\n", SCIPconsGetName(cons));

   /* update and check the watched variables, if they were changed since last processing */
   if( SCIPconsIsPropagationEnabled(cons) )
   {
      SCIP_CALL( processWatchedVars(scip, cons, eventhdlr, cutoff, infeasible, reduceddom, &mustcheck) );
   }
   else
      mustcheck = TRUE;

   if( mustcheck )
   {
      SCIP_Bool violated;

      SCIP_CALL( checkCons(scip, cons, sol, &violated) );
      if( violated )
      {
         /* constraint was infeasible -> reset age */
         SCIP_CALL( SCIPresetConsAge(scip, cons) );
         *infeasible = TRUE;

         /* register branching candidates */
         SCIP_CALL( registerBranchingCandidates(scip, cons, sol, &neednarybranch) );

         if( !neednarybranch )
            *registeredbrcand = TRUE;
      }
   }

   return SCIP_OKAY;
}

/** enforces a constraint by creating an n-ary branch consisting of a set of child nodes, each enforcing one literal
 */
static
SCIP_RETCODE createNAryBranch(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons,               /**< bound disjunction constraint to branch on */
   SCIP_SOL*             sol                 /**< solution which should be enforced (NULL for LP solution) */
   )
{
   SCIP_CONSDATA* consdata;
   SCIP_VAR** vars;
   SCIP_BOUNDTYPE* boundtypes;
   SCIP_Real* bounds;
   SCIP_Real varlb;
   SCIP_Real varub;
   int nvars;
   int v;

   SCIP_Real  priority;
   SCIP_Real  estimate;
   SCIP_NODE* node;

   assert(cons != NULL);
   assert(SCIPconsGetHdlr(cons) != NULL);
   assert(strcmp(SCIPconshdlrGetName(SCIPconsGetHdlr(cons)), CONSHDLR_NAME) == 0);

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);
   nvars = consdata->nvars;
   vars = consdata->vars;
   boundtypes = consdata->boundtypes;
   bounds = consdata->bounds;
   assert(nvars == 0 || vars != NULL);
   assert(nvars == 0 || boundtypes != NULL);
   assert(nvars == 0 || bounds != NULL);

   for( v = 0; v < nvars; ++v )
   {
      SCIP_VAR* var;

      var = vars[v];
      assert(var != NULL);

      /* constraint should be violated, so all bounds in the constraint have to be violated */
      assert( !(boundtypes[v] == SCIP_BOUNDTYPE_LOWER && isFeasGE(scip, var, SCIPgetSolVal(scip, sol, var), bounds[v])) && /*lint !e666*/
         !(boundtypes[v] == SCIP_BOUNDTYPE_UPPER && isFeasLE(scip, var, SCIPgetSolVal(scip, sol, var), bounds[v])) ); /*lint !e666*/

      varlb = SCIPcomputeVarLbLocal(scip, var);
      varub = SCIPcomputeVarUbLocal(scip, var);

      /* if literal is x >= varlb, but upper bound on x is < varlb, then this literal can never be satisfied,
       * thus there is no use in creating an extra child for it
       */
      if( boundtypes[v] == SCIP_BOUNDTYPE_LOWER && isFeasLT(scip, var, varub, bounds[v]) )
         continue;
      /* if literal is x <= varub, but lower bound on x is > varub, then this literal can never be satisfied,
       * thus there is no use in creating an extra child for it
       */
      if( boundtypes[v] == SCIP_BOUNDTYPE_UPPER && isFeasGT(scip, var, varlb, bounds[v]) )
         continue;
      /* if literal is always satisfied, then no need to branch on it */
      if( isLiteralSatisfied(scip, consdata, v) )
         continue;

      /* create a child that enforces the current literal */
      priority = SCIPcalcNodeselPriority(scip, var, boundtypes[v] == SCIP_BOUNDTYPE_LOWER ?
         SCIP_BRANCHDIR_UPWARDS : SCIP_BRANCHDIR_DOWNWARDS, bounds[v]);
      estimate = SCIPcalcChildEstimate  (scip, var, bounds[v]);

      SCIPdebugMsg(scip, " -> creating child to enforce: <%s> %c= %g (priority: %g, estimate: %g)\n",
         SCIPvarGetName(vars[v]), boundtypes[v] == SCIP_BOUNDTYPE_LOWER ? '>' : '<', bounds[v], priority, estimate);

      SCIP_CALL( SCIPcreateChild(scip, &node, priority, estimate) );

      /* enforce current literal */
      if( SCIPvarGetStatus(var) == SCIP_VARSTATUS_MULTAGGR )
      {
         SCIP_CONS* brcons;
         SCIP_Real  one;

         one = 1.0;

         if( boundtypes[v] == SCIP_BOUNDTYPE_LOWER )
         {
            SCIP_CALL( SCIPcreateConsLinear(scip, &brcons, "bounddisjbranch", 1, &var, &one, bounds[v], SCIPinfinity(scip),
               SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
               SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
               SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
               SCIPconsIsStickingAtNode(cons)) );
         }
         else
         {
            SCIP_CALL( SCIPcreateConsLinear(scip, &brcons, "bounddisjbranch", 1, &var, &one, -SCIPinfinity(scip), bounds[v],
               SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
               SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
               SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
               SCIPconsIsStickingAtNode(cons)) );
         }
         SCIP_CALL( SCIPaddConsNode(scip, node, brcons, NULL) );
         SCIP_CALL( SCIPreleaseCons(scip, &brcons) );
      }
      else
      {
         assert(SCIPvarIsActive(var));
         if( boundtypes[v] == SCIP_BOUNDTYPE_LOWER )
         {
            SCIP_CALL( SCIPchgVarLbNode(scip, node, var, bounds[v]) );
         }
         else
         {
            SCIP_CALL( SCIPchgVarUbNode(scip, node, var, bounds[v]) );
         }
      }

      /* delete bound disjunction constraint from child node */
      SCIP_CALL( SCIPdelConsNode(scip, node, cons) );
   }

   return SCIP_OKAY;
}

/** helper function to enforce constraints */
static
SCIP_RETCODE enforceConstraint(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONSHDLR*        conshdlr,           /**< constraint handler */
   SCIP_CONS**           conss,              /**< constraints to process */
   int                   nconss,             /**< number of constraints */
   SCIP_SOL*             sol,                /**< solution to enforce (NULL for the LP solution) */
   SCIP_RESULT*          result              /**< pointer to store the result of the enforcing call */
   )
{
   SCIP_CONSHDLRDATA* conshdlrdata;
   SCIP_Bool cutoff;
   SCIP_Bool infeasible;
   SCIP_Bool reduceddom;
   SCIP_Bool registeredbrcand;
   SCIP_Bool infeasiblecons;
   int c;
   int nnarybranchconsvars;
   SCIP_CONS* narybranchcons; /* constraint that is a candidate for an n-ary branch */

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(nconss == 0 || conss != NULL);
   assert(result != NULL);

   SCIPdebugMsg(scip, "Enforcing %d bound disjunction constraints for %s solution\n", nconss, sol == NULL ? "LP" : "relaxation");

   *result = SCIP_FEASIBLE;

   conshdlrdata = SCIPconshdlrGetData(conshdlr);
   assert(conshdlrdata != NULL);

   cutoff = FALSE;
   infeasible = FALSE;
   reduceddom = FALSE;
   registeredbrcand = FALSE;
   narybranchcons = NULL;
   nnarybranchconsvars = INT_MAX;

   /* check all bound disjunction constraints for feasibility */
   for( c = 0; c < nconss && !cutoff && !reduceddom; ++c )
   {
      infeasiblecons = FALSE;
      SCIP_CALL( enforceCurrentSol(scip, conss[c], sol, conshdlrdata->eventhdlr, &cutoff, &infeasiblecons, &reduceddom,
            &registeredbrcand) );
      infeasible |= infeasiblecons;
      if( infeasiblecons && !registeredbrcand )
      {
         /* if cons. c has less literals than the previous candidate for an n-ary branch, then keep cons. c as candidate for n-ary branch */
         if( narybranchcons == NULL || SCIPconsGetData(conss[c])->nvars < nnarybranchconsvars )
         {
            narybranchcons = conss[c];
            nnarybranchconsvars = SCIPconsGetData(narybranchcons)->nvars;
            assert(nnarybranchconsvars > 0);
         }
      }
   }

   if( cutoff )
      *result = SCIP_CUTOFF;
   else if( reduceddom )
      *result = SCIP_REDUCEDDOM;
   else if( infeasible )
   {
      if( registeredbrcand )
      {
         *result = SCIP_INFEASIBLE;
      }
      else
      {
         SCIP_CALL( createNAryBranch(scip, narybranchcons, sol) );
         *result = SCIP_BRANCHED;
      }
   }

   return SCIP_OKAY;
}

/**@} */

/**@name Upgrading methods for special quadratic constraint
 *
 */

/** upgrades quadratic complementarity constraints into a bounddisjunction constraint
 * If constraint is of form (x - a) * (y - b) = 0 with x >= a and y >= b for some a and b,
 * then upgrade to bounddisjunction constraint "x <= a or y <= b".
 * If constraint is of form (x - a) * (y - b) >= 0,
 * then upgrade to bounddisjunction constraints "x >= a or y <= b" and "x <= a or y >= b".
 */
static
SCIP_DECL_QUADCONSUPGD(upgradeConsQuadratic)
{  /*lint --e{715}*/
   char name[SCIP_MAXSTRLEN];
   SCIP_BOUNDTYPE boundtypes[2];
   SCIP_Real bounds[2];
   SCIP_VAR* xy[2];
   SCIP_QUADVARTERM* quadvarterms;
   SCIP_Real coefxy;
   SCIP_Real coefx;
   SCIP_Real coefy;
   SCIP_Real lhs;
   SCIP_Real rhs;
   SCIP_Real a;
   SCIP_Real b;
   SCIP_VAR* x;
   SCIP_VAR* y;

   assert(scip != NULL);
   assert(cons != NULL);
   assert(nupgdconss != NULL);
   assert(upgdconss  != NULL);

   *nupgdconss = 0;

   SCIPdebugMsg(scip, "upgradeConsQuadratic called for constraint <%s>\n", SCIPconsGetName(cons));
   SCIPdebugPrintCons(scip, cons, NULL);

   if( SCIPgetNLinearVarsQuadratic(scip, cons) != 0 )
      return SCIP_OKAY;
   if( SCIPgetNQuadVarTermsQuadratic(scip, cons) != 2 )
      return SCIP_OKAY;
   if( SCIPgetNBilinTermsQuadratic(scip, cons) != 1 )
      return SCIP_OKAY;
   /* do not upgrade x*y <=/== rhs with x (or y) binary
    * the reformulation for such terms in cons_quadratic should handle this better
    */
   if( nbinquad > 0 )
      return SCIP_OKAY;

   lhs = SCIPgetLhsQuadratic(scip, cons);
   rhs = SCIPgetRhsQuadratic(scip, cons);

   /* we don't want a free constraint */
   if( SCIPisInfinity(scip, -lhs) && SCIPisInfinity(scip, rhs) )
      return SCIP_OKAY;

   /* we currently don't want a ranged constraint (could upgrade at most one side) */
   if( !SCIPisInfinity(scip, -lhs) && !SCIPisInfinity(scip, rhs) && !SCIPisEQ(scip, lhs, rhs) )
      return SCIP_OKAY;

   quadvarterms = SCIPgetQuadVarTermsQuadratic(scip, cons);

   /* we don't want square terms */
   if( !SCIPisZero(scip, quadvarterms[0].sqrcoef) || !SCIPisZero(scip, quadvarterms[1].sqrcoef) )
      return SCIP_OKAY;

   x = quadvarterms[0].var;
   y = quadvarterms[1].var;
   assert(x != y);

   coefx = quadvarterms[0].lincoef;
   coefy = quadvarterms[1].lincoef;

   coefxy = SCIPgetBilinTermsQuadratic(scip, cons)[0].coef;
   assert(SCIPgetBilinTermsQuadratic(scip, cons)[0].var1 == x || SCIPgetBilinTermsQuadratic(scip, cons)[0].var1 == y);
   assert(SCIPgetBilinTermsQuadratic(scip, cons)[0].var2 == x || SCIPgetBilinTermsQuadratic(scip, cons)[0].var2 == y);
   assert(!SCIPisZero(scip, coefxy));

   /* divide by coefxy */
   coefx /= coefxy;
   coefy /= coefxy;
   if( coefxy > 0.0 )
   {
      if( !SCIPisInfinity(scip, -lhs) )
         lhs /= coefxy;
      if( !SCIPisInfinity(scip,  rhs) )
         rhs /= coefxy;
   }
   else
   {
      SCIP_Real tmp;

      if( !SCIPisInfinity(scip,  rhs) )
         tmp = rhs / coefxy;
      else
         tmp = -SCIPinfinity(scip);
      if( !SCIPisInfinity(scip, -lhs) )
         rhs = lhs / coefxy;
      else
         rhs = SCIPinfinity(scip);
      lhs = tmp;
   }

   /* now have form lhs <= x*y + coefx x + coefy y <= rhs
    *   <-> lhs + coefx * coefy <= (x + coefy) * (y + coefx) <= rhs + coefx * coefy
    */

   /* handle case (x + coefy) * (y + coefx) == rhs + coefx * coefy */
   if( SCIPisEQ(scip, lhs, rhs) )
   {
      /* check whether rhs + coefx * coefy == 0 */
      if( !SCIPisZero(scip, rhs + coefx * coefy) )
         return SCIP_OKAY;

      a = -coefy;
      b = -coefx;

      /* now have complementarity form x = a or y = b */

      /* we can write this as up to four bounddisjunction constraint:
       *   (x >= a or y >= b) and (x <= a or y >= b) and (x >= a or y <= b) and (x <= a or y <= b)
       *
       * count whether we need to create 1, 2, or 4 constraints
       */
      if( !SCIPisGE(scip, SCIPvarGetLbGlobal(x), a) && !SCIPisLE(scip, SCIPvarGetUbGlobal(x), a) )
         *nupgdconss = 2;
      else
         *nupgdconss = 1;

      if( !SCIPisGE(scip, SCIPvarGetLbGlobal(y), b) && !SCIPisLE(scip, SCIPvarGetUbGlobal(y), b) )
         *nupgdconss *= 2;

      if( upgdconsssize < *nupgdconss )
      {
         /* signal that we need more memory */
         *nupgdconss = -*nupgdconss;
         return SCIP_OKAY;
      }

      xy[0] = x;
      xy[1] = y;
      bounds[0] = a;
      bounds[1] = b;
      if( *nupgdconss == 1 )
      {
         boundtypes[0] = SCIPisGE(scip, SCIPvarGetLbGlobal(x), a) ? SCIP_BOUNDTYPE_UPPER : SCIP_BOUNDTYPE_LOWER;
         boundtypes[1] = SCIPisGE(scip, SCIPvarGetLbGlobal(y), b) ? SCIP_BOUNDTYPE_UPPER : SCIP_BOUNDTYPE_LOWER;
         SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[0], SCIPconsGetName(cons),
            2, xy, boundtypes, bounds,
            SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
            SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
            SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
            SCIPconsIsStickingAtNode(cons)) );

         SCIPdebugMsg(scip, "created bounddisjunction constraint:\n");
         SCIPdebugPrintCons(scip, upgdconss[0], NULL);

         return SCIP_OKAY;
      }
      else if( SCIPisGE(scip, SCIPvarGetLbGlobal(x), a) || SCIPisLE(scip, SCIPvarGetUbGlobal(x), a) )
      {
         assert(!SCIPisGE(scip, SCIPvarGetLbGlobal(y), b) && !SCIPisLE(scip, SCIPvarGetUbGlobal(y), b));
         assert(*nupgdconss == 2);

         boundtypes[0] = SCIPisGE(scip, SCIPvarGetLbGlobal(x), a) ? SCIP_BOUNDTYPE_UPPER : SCIP_BOUNDTYPE_LOWER;

         /* create constraint with y >= b */
         boundtypes[1] = SCIP_BOUNDTYPE_LOWER;
         (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_lower", SCIPconsGetName(cons));
         SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[0], name,
            2, xy, boundtypes, bounds,
            SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
            SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
            SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
            SCIPconsIsStickingAtNode(cons)) );

         /* create constraint with y <= b */
         boundtypes[1] = SCIP_BOUNDTYPE_UPPER;
         (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_upper", SCIPconsGetName(cons));
         SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[1], name,
            2, xy, boundtypes, bounds,
            SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
            SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
            SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
            SCIPconsIsStickingAtNode(cons)) );

         SCIPdebugMsg(scip, "created bounddisjunction constraints:\n");
         SCIPdebugPrintCons(scip, upgdconss[0], NULL);
         SCIPdebugPrintCons(scip, upgdconss[1], NULL);
      }
      else if( SCIPisGE(scip, SCIPvarGetLbGlobal(y), b) || SCIPisLE(scip, SCIPvarGetUbGlobal(y), b) )
      {
         assert(!SCIPisEQ(scip, SCIPvarGetLbGlobal(x), a) && !SCIPisEQ(scip, SCIPvarGetUbGlobal(x), a));
         assert(*nupgdconss == 2);

         boundtypes[1] = SCIPisGE(scip, SCIPvarGetLbGlobal(y), b) ? SCIP_BOUNDTYPE_UPPER : SCIP_BOUNDTYPE_LOWER;

         /* create constraint with x >= a */
         boundtypes[0] = SCIP_BOUNDTYPE_LOWER;
         (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_lower", SCIPconsGetName(cons));
         SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[0], name,
            2, xy, boundtypes, bounds,
            SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
            SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
            SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
            SCIPconsIsStickingAtNode(cons)) );

         /* create constraint with x <= a */
         boundtypes[0] = SCIP_BOUNDTYPE_UPPER;
         (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_lower", SCIPconsGetName(cons));
         SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[1], name,
            2, xy, boundtypes, bounds,
            SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
            SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
            SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
            SCIPconsIsStickingAtNode(cons)) );

         SCIPdebugMsg(scip, "created bounddisjunction constraints:\n");
         SCIPdebugPrintCons(scip, upgdconss[0], NULL);
         SCIPdebugPrintCons(scip, upgdconss[1], NULL);
      }
      else
      {
         assert(!SCIPisGE(scip, SCIPvarGetLbGlobal(x), a) && !SCIPisLE(scip, SCIPvarGetUbGlobal(x), a));
         assert(!SCIPisGE(scip, SCIPvarGetLbGlobal(y), b) && !SCIPisLE(scip, SCIPvarGetUbGlobal(y), b));
         assert(*nupgdconss == 4);

         /* create constraint x >= a or y >= a */
         boundtypes[0] = SCIP_BOUNDTYPE_LOWER;
         boundtypes[1] = SCIP_BOUNDTYPE_LOWER;
         (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_lower_lower", SCIPconsGetName(cons));
         SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[0], name,
            2, xy, boundtypes, bounds,
            SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
            SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
            SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
            SCIPconsIsStickingAtNode(cons)) );

         /* create constraint x >= a or y <= a */
         boundtypes[0] = SCIP_BOUNDTYPE_LOWER;
         boundtypes[1] = SCIP_BOUNDTYPE_UPPER;
         (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_lower_upper", SCIPconsGetName(cons));
         SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[1], name,
            2, xy, boundtypes, bounds,
            SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
            SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
            SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
            SCIPconsIsStickingAtNode(cons)) );

         /* create constraint x <= a or y >= a */
         boundtypes[0] = SCIP_BOUNDTYPE_UPPER;
         boundtypes[1] = SCIP_BOUNDTYPE_LOWER;
         (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_upper_lower", SCIPconsGetName(cons));
         SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[2], name,
            2, xy, boundtypes, bounds,
            SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
            SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
            SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
            SCIPconsIsStickingAtNode(cons)) );

         /* create constraint x <= a or y <= a */
         boundtypes[0] = SCIP_BOUNDTYPE_UPPER;
         boundtypes[1] = SCIP_BOUNDTYPE_UPPER;
         (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_upper_upper", SCIPconsGetName(cons));
         SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[3], name,
            2, xy, boundtypes, bounds,
            SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
            SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
            SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
            SCIPconsIsStickingAtNode(cons)) );

         SCIPdebugMsg(scip, "created bounddisjunction constraints:\n");
         SCIPdebugPrintCons(scip, upgdconss[0], NULL);
         SCIPdebugPrintCons(scip, upgdconss[1], NULL);
         SCIPdebugPrintCons(scip, upgdconss[2], NULL);
         SCIPdebugPrintCons(scip, upgdconss[3], NULL);
      }

      return SCIP_OKAY;
   }

   /* handle case (x + coefy) * (y + coefx) <= rhs + coefx * coefy */
   if( !SCIPisInfinity(scip, rhs) )
   {
      assert(SCIPisInfinity(scip, -lhs));

      /* check whether rhs + coefx * coefy == 0 */
      if( !SCIPisZero(scip, rhs + coefx * coefy) )
         return SCIP_OKAY;

      a = -coefy;
      b = -coefx;

      /* now have form (x >= a and y <= b) or (x <= a and y >= b)
       * which is equivalent to (x >= a or y >= b) and (x <= a or y <= b)
       * the latter can be represented as two bound disjunction constraints
       */

      if( upgdconsssize < 2 )
      {
         /* signal that we need more memory */
         *nupgdconss = -2;
         return SCIP_OKAY;
      }

      xy[0] = x;
      xy[1] = y;
      bounds[0] = a;
      bounds[1] = b;

      /* create constraint x >= a or y >= b */
      boundtypes[0] = SCIP_BOUNDTYPE_LOWER;
      boundtypes[1] = SCIP_BOUNDTYPE_LOWER;
      (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_lower", SCIPconsGetName(cons));
      SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[0], name,
         2, xy, boundtypes, bounds,
         SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
         SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
         SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
         SCIPconsIsStickingAtNode(cons)) );

      /* create constraint x <= a or y <= b */
      boundtypes[0] = SCIP_BOUNDTYPE_UPPER;
      boundtypes[1] = SCIP_BOUNDTYPE_UPPER;
      (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_upper", SCIPconsGetName(cons));
      SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[1], name,
         2, xy, boundtypes, bounds,
         SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
         SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
         SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
         SCIPconsIsStickingAtNode(cons)) );

      SCIPdebugMsg(scip, "created bounddisjunction constraints:\n");
      SCIPdebugPrintCons(scip, upgdconss[0], NULL);
      SCIPdebugPrintCons(scip, upgdconss[1], NULL);

      *nupgdconss = 2;

      return SCIP_OKAY;
   }

   /* handle remaining case (x + coefy) * (y + coefx) >= lhs + coefx * coefy */
   {
      assert(!SCIPisInfinity(scip, -lhs));
      assert( SCIPisInfinity(scip,  rhs));

      /* check whether lhs + coefx * coefy == 0 */
      if( !SCIPisZero(scip, lhs + coefx * coefy) )
         return SCIP_OKAY;

      a = -coefy;
      b = -coefx;

      /* now have form (x >= a and y >= b) or (x <= a and y <= b)
       * which is equivalent to (x >= a or y <= b) and (x <= a or y >= b)
       * the latter can be represented as two bound disjunction constraints
       */

      if( upgdconsssize < 2 )
      {
         /* signal that we need more memory */
         *nupgdconss = -2;
         return SCIP_OKAY;
      }

      xy[0] = x;
      xy[1] = y;
      bounds[0] = a;
      bounds[1] = b;

      /* create constraint x >= a or y <= b */
      boundtypes[0] = SCIP_BOUNDTYPE_LOWER;
      boundtypes[1] = SCIP_BOUNDTYPE_UPPER;
      (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_lower", SCIPconsGetName(cons));
      SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[0], name,
         2, xy, boundtypes, bounds,
         SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
         SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
         SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
         SCIPconsIsStickingAtNode(cons)) );

      /* create constraint x <= a or y >= b */
      boundtypes[0] = SCIP_BOUNDTYPE_UPPER;
      boundtypes[1] = SCIP_BOUNDTYPE_LOWER;
      (void) SCIPsnprintf(name, SCIP_MAXSTRLEN, "%s_upper", SCIPconsGetName(cons));
      SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &upgdconss[1], name,
         2, xy, boundtypes, bounds,
         SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
         SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
         SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
         SCIPconsIsStickingAtNode(cons)) );

      SCIPdebugMsg(scip, "created bounddisjunction constraints:\n");
      SCIPdebugPrintCons(scip, upgdconss[0], NULL);
      SCIPdebugPrintCons(scip, upgdconss[1], NULL);

      *nupgdconss = 2;
   }

   return SCIP_OKAY;
}

/**@} */

/**@name Callback methods of constraint handler
 *
 * @{
 */

/** copy method for constraint handler plugins (called when SCIP copies plugins) */
static
SCIP_DECL_CONSHDLRCOPY(conshdlrCopyBounddisjunction)
{  /*lint --e{715}*/
   assert(scip != NULL);
   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);

   /* call inclusion method of constraint handler */
   SCIP_CALL( SCIPincludeConshdlrBounddisjunction(scip) );

   *valid = TRUE;

   return SCIP_OKAY;
}

/** destructor of constraint handler to free constraint handler data (called when SCIP is exiting) */
static
SCIP_DECL_CONSFREE(consFreeBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSHDLRDATA* conshdlrdata;

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(scip != NULL);

   /* free constraint handler data */
   conshdlrdata = SCIPconshdlrGetData(conshdlr);
   assert(conshdlrdata != NULL);

   SCIP_CALL( conshdlrdataFree(scip, &conshdlrdata) );

   SCIPconshdlrSetData(conshdlr, NULL);

   return SCIP_OKAY;
}


/** presolving deinitialization method of constraint handler (called after presolving has been finished) */
static
SCIP_DECL_CONSEXITPRE(consExitpreBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSHDLRDATA* conshdlrdata;
   SCIP_CONS* cons;
   SCIP_Bool redundant;
   int c;

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(scip != NULL);

   conshdlrdata = SCIPconshdlrGetData(conshdlr);
   assert(conshdlrdata != NULL);

   /* fast processing of constraints, apply global bounds and remove fixed variables */
   for( c = 0; c < nconss; ++c )
   {
      cons = conss[c];
      assert(cons != NULL);

      SCIPdebugMsg(scip, "exit-presolving bound disjunction constraint <%s>\n", SCIPconsGetName(cons));

      if( SCIPconsIsDeleted(cons) )
         continue;

      /* remove all literals that are violated in global bounds, check redundancy due to global bounds */
      SCIP_CALL( applyGlobalBounds(scip, cons, conshdlrdata->eventhdlr, &redundant) );

      if( !redundant )
      {
         /* replace variables by their representative active (or multi-aggregated) variables */
         SCIP_CALL( removeFixedVariables(scip, cons, conshdlrdata->eventhdlr, &redundant) );
      }

      if( redundant && SCIPconsIsAdded(cons) )
      {
         SCIPdebugMsg(scip, "bound disjunction constraint <%s> is redundant\n", SCIPconsGetName(cons));
         SCIP_CALL( SCIPdelCons(scip, cons) );
      }
   }

   return SCIP_OKAY;
}


/** frees specific constraint data */
static
SCIP_DECL_CONSDELETE(consDeleteBounddisjunction)
{  /*lint --e{715}*/
   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(consdata != NULL);
   assert(*consdata != NULL);

   /* free LP row and bound disjunction constraint */
   SCIP_CALL( consdataFree(scip, consdata) );

   return SCIP_OKAY;
}


/** transforms constraint data into data belonging to the transformed problem */ 
static
SCIP_DECL_CONSTRANS(consTransBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSDATA* sourcedata;
   SCIP_CONSDATA* targetdata;

   /*debugMsg(scip, "Trans method of bound disjunction constraints\n");*/

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(SCIPgetStage(scip) == SCIP_STAGE_TRANSFORMING);
   assert(sourcecons != NULL);
   assert(targetcons != NULL);

   sourcedata = SCIPconsGetData(sourcecons);
   assert(sourcedata != NULL);

   /* create constraint data for target constraint */
   SCIP_CALL( consdataCreate(scip, &targetdata, sourcedata->nvars, sourcedata->vars,
         sourcedata->boundtypes, sourcedata->bounds) );

   /* create target constraint */
   SCIP_CALL( SCIPcreateCons(scip, targetcons, SCIPconsGetName(sourcecons), conshdlr, targetdata,
         SCIPconsIsInitial(sourcecons), SCIPconsIsSeparated(sourcecons), SCIPconsIsEnforced(sourcecons),
         SCIPconsIsChecked(sourcecons), SCIPconsIsPropagated(sourcecons),
         SCIPconsIsLocal(sourcecons), SCIPconsIsModifiable(sourcecons), 
         SCIPconsIsDynamic(sourcecons), SCIPconsIsRemovable(sourcecons), SCIPconsIsStickingAtNode(sourcecons)) );

   return SCIP_OKAY;
}


/** constraint enforcing method of constraint handler for LP solutions */
static
SCIP_DECL_CONSENFOLP(consEnfolpBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CALL( enforceConstraint(scip, conshdlr, conss, nconss, NULL, result) );

   return SCIP_OKAY;
}


/** constraint enforcing method of constraint handler for relaxation solutions */
static
SCIP_DECL_CONSENFORELAX(consEnforelaxBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CALL( enforceConstraint(scip, conshdlr, conss, nconss, sol, result) );

   return SCIP_OKAY;
}


/** constraint enforcing method of constraint handler for pseudo solutions */
static
SCIP_DECL_CONSENFOPS(consEnfopsBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSHDLRDATA* conshdlrdata;
   SCIP_Bool cutoff;
   SCIP_Bool infeasible;
   SCIP_Bool reduceddom;
   SCIP_Bool registeredbrcand;
   int c;
   SCIP_CONS* narybranchcons; /* constraint that is a candidate for an n-ary branch */

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(nconss == 0 || conss != NULL);
   assert(result != NULL);

   SCIPdebugMsg(scip, "pseudo enforcing %d bound disjunction constraints\n", nconss);

   *result = SCIP_FEASIBLE;

   conshdlrdata = SCIPconshdlrGetData(conshdlr);
   assert(conshdlrdata != NULL);

   cutoff = FALSE;
   infeasible = FALSE;
   reduceddom = FALSE;
   registeredbrcand = FALSE;
   narybranchcons = NULL;

   /* check all bound disjunction constraints for feasibility */
   for( c = 0; c < nconss && !cutoff && !reduceddom; ++c )
   {
      SCIP_CALL( enforceCurrentSol(scip, conss[c], NULL, conshdlrdata->eventhdlr, &cutoff, &infeasible, &reduceddom,
            &registeredbrcand) );
      if( infeasible && !registeredbrcand )
      {
         /* if cons. c has less literals than the previous candidate for an n-ary branch, then keep cons. c as candidate for n-ary branch */
         if( !narybranchcons || SCIPconsGetData(conss[c])->nvars < SCIPconsGetData(narybranchcons)->nvars )
            narybranchcons = conss[c];
      }
   }

   if( cutoff )
      *result = SCIP_CUTOFF;
   else if( reduceddom )
      *result = SCIP_REDUCEDDOM;
   else if( infeasible )
   {
      if( registeredbrcand )
      {
         *result = SCIP_INFEASIBLE;
      }
      else
      {
         SCIP_CALL( createNAryBranch(scip, narybranchcons, NULL) );
         *result = SCIP_BRANCHED;
      }
   }

   return SCIP_OKAY;
}


/** feasibility check method of constraint handler for integral solutions */
static
SCIP_DECL_CONSCHECK(consCheckBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONS* cons;
   SCIP_CONSDATA* consdata;
   int c;

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(nconss == 0 || conss != NULL);
   assert(result != NULL);

   *result = SCIP_FEASIBLE;

   /* check all bound disjunction constraints for feasibility */
   for( c = 0; c < nconss && (*result == SCIP_FEASIBLE || completely); ++c )
   {
      SCIP_Bool violated;

      cons = conss[c];
      consdata = SCIPconsGetData(cons);
      assert(consdata != NULL);

      SCIP_CALL( checkCons(scip, cons, sol, &violated) );
      if( violated )
      {
         if( printreason )
         {
            int v;

            SCIP_CALL( SCIPprintCons(scip, cons, NULL) );
            SCIPinfoMessage(scip, NULL, ";\nviolation: ");
            for( v = 0; v < consdata->nvars; ++v )
            {
               assert(consdata->vars[v] != NULL);
               if( v > 0 )
                  SCIPinfoMessage(scip, NULL, ", ");
               SCIPinfoMessage(scip, NULL, "<%s> = %.15g", 
                  SCIPvarGetName(consdata->vars[v]), SCIPgetSolVal(scip, sol, consdata->vars[v]));
            }
            SCIPinfoMessage(scip, NULL, ")\n");
         }

         /* constraint is violated */
         *result = SCIP_INFEASIBLE;
      }
   }

   return SCIP_OKAY;
}


/** domain propagation method of constraint handler */
static
SCIP_DECL_CONSPROP(consPropBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSHDLRDATA* conshdlrdata;
   SCIP_Bool cutoff;
   SCIP_Bool infeasible;
   SCIP_Bool reduceddom;
   SCIP_Bool mustcheck;
   SCIP_Bool consreduceddom;
   int c;

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(nconss == 0 || conss != NULL);
   assert(result != NULL);

   conshdlrdata = SCIPconshdlrGetData(conshdlr);
   assert(conshdlrdata != NULL);

   cutoff = FALSE;
   infeasible = FALSE;
   reduceddom = FALSE;

   /* propagate all useful bound disjunction constraints */
   for( c = 0; c < nusefulconss && !cutoff; ++c )
   {
      SCIP_CALL( processWatchedVars(scip, conss[c], conshdlrdata->eventhdlr,
            &cutoff, &infeasible, &consreduceddom, &mustcheck) );
      reduceddom = reduceddom || consreduceddom;
   }

   /* return the correct result */
   if( cutoff )
      *result = SCIP_CUTOFF;
   else if( reduceddom )
      *result = SCIP_REDUCEDDOM;
   else
      *result = SCIP_DIDNOTFIND;

   return SCIP_OKAY;
}


/** presolving method of constraint handler */
static
SCIP_DECL_CONSPRESOL(consPresolBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSHDLRDATA* conshdlrdata;
   SCIP_CONS* cons;
   SCIP_CONSDATA* consdata;
   SCIP_Bool infeasible;
   SCIP_Bool redundant;
   SCIP_Bool tightened;
   int c;

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(scip != NULL);
   assert(result != NULL);

   *result = SCIP_DIDNOTFIND;

   conshdlrdata = SCIPconshdlrGetData(conshdlr);
   assert(conshdlrdata != NULL);

   /* process constraints */
   for( c = 0; c < nconss && *result != SCIP_CUTOFF && !SCIPisStopped(scip); ++c )
   {
      cons = conss[c];
      assert(cons != NULL);
      consdata = SCIPconsGetData(cons);
      assert(consdata != NULL);

      SCIPdebugMsg(scip, "presolving bound disjunction constraint <%s>\n", SCIPconsGetName(cons));

      /* force presolving the constraint in the initial round */
      if( nrounds == 0 )
      {
         SCIP_CALL( SCIPenableConsPropagation(scip, cons) );
      }

      /* remove all literals that are violated in global bounds, check redundancy due to global bounds */
      SCIP_CALL( applyGlobalBounds(scip, cons, conshdlrdata->eventhdlr, &redundant) );

      if( !redundant )
      {
         /* replace variables by their representative active (or multi-aggregated) variables */
         SCIP_CALL( removeFixedVariables(scip, cons, conshdlrdata->eventhdlr, &redundant) );
      }

      /**@todo find pairs of negated variables in constraint: constraint is redundant */
      /**@todo find sets of equal variables in constraint: multiple entries of variable can be replaced by single entry */

      if( redundant )
      {
         SCIPdebugMsg(scip, "bound disjunction constraint <%s> is redundant\n", SCIPconsGetName(cons));
         SCIP_CALL( SCIPdelCons(scip, cons) );
         (*ndelconss)++;
         *result = SCIP_SUCCESS;
         continue;
      }
      else if( !SCIPconsIsModifiable(cons) )
      {
         /* if unmodifiable constraint has no variables, it is infeasible,
          * if unmodifiable constraint has only one variable, the literal can be satisfied and the constraint deleted
          */
         if( consdata->nvars == 0 )
         {
            SCIPdebugMsg(scip, "bound disjunction constraint <%s> is infeasible\n", SCIPconsGetName(cons));
            *result = SCIP_CUTOFF;
            return SCIP_OKAY;
         }
         else if( consdata->nvars == 1 )
         {
            SCIPdebugMsg(scip, "bound disjunction constraint <%s> has only one undecided literal\n",
               SCIPconsGetName(cons));

            assert(consdata->vars != NULL);
            assert(!isLiteralSatisfied(scip, consdata, 0));
            assert(!isLiteralViolated(scip, consdata, 0));

            if( SCIPvarIsActive(consdata->vars[0]) )
            {
               if( consdata->boundtypes[0] == SCIP_BOUNDTYPE_LOWER )
               {
                  SCIP_CALL( SCIPtightenVarLb(scip, consdata->vars[0], consdata->bounds[0], TRUE, &infeasible, &tightened) );
               }
               else
               {
                  SCIP_CALL( SCIPtightenVarUb(scip, consdata->vars[0], consdata->bounds[0], TRUE, &infeasible, &tightened) );
               }
               if( infeasible )
               {
                  SCIPdebugMsg(scip, " -> infeasible fixing\n");
                  *result = SCIP_CUTOFF;
                  return SCIP_OKAY;
               }
               assert(tightened);
               (*nchgbds)++;
            }
            else
            {
               /* upgrade to a linear constraint, if vars[0] is multi-aggregated */
               SCIP_CONS* lincons;
               SCIP_Real one;

               assert(SCIPvarGetStatus(consdata->vars[0]) == SCIP_VARSTATUS_MULTAGGR);

               one = 1.0;
               if( consdata->boundtypes[0] == SCIP_BOUNDTYPE_LOWER )
               {
                  SCIP_CALL( SCIPcreateConsLinear(scip, &lincons, SCIPconsGetName(cons),
                     1, &consdata->vars[0], &one, consdata->bounds[0], SCIPinfinity(scip),
                     SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
                     SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
                     SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
                     SCIPconsIsStickingAtNode(cons)) );
               }
               else
               {
                  SCIP_CALL( SCIPcreateConsLinear(scip, &lincons, SCIPconsGetName(cons),
                     1, &consdata->vars[0], &one, -SCIPinfinity(scip), consdata->bounds[0],
                     SCIPconsIsInitial(cons), SCIPconsIsSeparated(cons), SCIPconsIsEnforced(cons),
                     SCIPconsIsChecked(cons), SCIPconsIsPropagated(cons),  SCIPconsIsLocal(cons),
                     SCIPconsIsModifiable(cons), SCIPconsIsDynamic(cons), SCIPconsIsRemovable(cons),
                     SCIPconsIsStickingAtNode(cons)) );
               }
               SCIP_CALL( SCIPaddCons(scip, lincons) );
               SCIP_CALL( SCIPreleaseCons(scip, &lincons) );
               (*nupgdconss)++;
            }

            SCIP_CALL( SCIPdelCons(scip, cons) );
            (*ndelconss)++;
            *result = SCIP_SUCCESS;
            continue;
         }
         else
         {
            /* try to upgrade the bounddisjunction constraint */
            SCIP_CALL( upgradeCons(scip, cons, ndelconss, naddconss) );
         }
      }
   }

   /**@todo preprocess pairs of bound disjunction constraints */

   return SCIP_OKAY;
}


/** propagation conflict resolving method of constraint handler */
static
SCIP_DECL_CONSRESPROP(consRespropBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSDATA* consdata;
   SCIP_VAR** vars;
   SCIP_BOUNDTYPE* boundtypes;
#ifndef NDEBUG
   SCIP_Real* bounds;
#endif
   int v;

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(cons != NULL);
   assert(infervar != NULL);
   assert(result != NULL);

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);
   assert(consdata->vars != NULL);
   assert(consdata->nvars > 0);
   assert(0 <= inferinfo && inferinfo < consdata->nvars);
   assert(consdata->vars[inferinfo] == infervar);

   vars = consdata->vars;
   boundtypes = consdata->boundtypes;
#ifndef NDEBUG
   bounds = consdata->bounds;
   assert(bounds != NULL);
#endif
   assert(boundtypes != NULL);

   SCIPdebugMsg(scip, "conflict resolving method of bound disjunction constraint handler\n");

   /* the only deductions are bounds tightened to a literal's bound on bound disjunction constraints where all other
    * literals are violated
    */
   assert((boundtypes[inferinfo] == SCIP_BOUNDTYPE_LOWER
         && SCIPisFeasGE(scip, SCIPgetVarLbAtIndex(scip, infervar, bdchgidx, TRUE), bounds[inferinfo]))
      || (boundtypes[inferinfo] == SCIP_BOUNDTYPE_UPPER
         && SCIPisFeasLE(scip, SCIPgetVarUbAtIndex(scip, infervar, bdchgidx, TRUE), bounds[inferinfo])));

   for( v = 0; v < consdata->nvars; ++v )
   {
      if( v != inferinfo )
      {
         assert(consdata->vars[v] != infervar || consdata->boundtypes[v] != consdata->boundtypes[inferinfo]);

         /* the reason literal must have been violated
          * we do not check for multi-aggregated variables, since SCIPvarGetXbAtIndex is not implemented for them */
         /* Use a weaker comparison to SCIPvarGetXbAtIndex here (i.e., SCIPisXT instead of SCIPisFeasXT),
          * because SCIPvarGetXbAtIndex might differ from the local bound at time bdchgidx by epsilon. */
         assert(SCIPvarGetStatus(vars[v]) == SCIP_VARSTATUS_MULTAGGR
            || (boundtypes[v] == SCIP_BOUNDTYPE_LOWER
               && SCIPisLT(scip, SCIPgetVarUbAtIndex(scip, vars[v], bdchgidx, TRUE), bounds[v]))
            || (boundtypes[v] == SCIP_BOUNDTYPE_UPPER
               && SCIPisGT(scip, SCIPgetVarLbAtIndex(scip, vars[v], bdchgidx, TRUE), bounds[v])));
         SCIP_CALL( SCIPaddConflictBd(scip, vars[v], SCIPboundtypeOpposite(boundtypes[v]), bdchgidx) );
      }
   }

   *result = SCIP_SUCCESS;

   return SCIP_OKAY;
}


/** variable rounding lock method of constraint handler */
static
SCIP_DECL_CONSLOCK(consLockBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSDATA* consdata;
   int i;

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   /* lock every single coefficient */
   for( i = 0; i < consdata->nvars; ++i )
   {
      if( consdata->boundtypes[i] == SCIP_BOUNDTYPE_LOWER )
      {
         SCIP_CALL( SCIPaddVarLocks(scip, consdata->vars[i], nlockspos, nlocksneg) );
      }
      else
      {
         SCIP_CALL( SCIPaddVarLocks(scip, consdata->vars[i], nlocksneg, nlockspos) );
      }
   }

   return SCIP_OKAY;
}


/** constraint activation notification method of constraint handler */
static
SCIP_DECL_CONSACTIVE(consActiveBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSHDLRDATA* conshdlrdata;
   SCIP_CONSDATA* consdata;

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(cons != NULL);
   assert(SCIPconsIsTransformed(cons));

   conshdlrdata = SCIPconshdlrGetData(conshdlr);
   assert(conshdlrdata != NULL);
   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);
   assert(consdata->watchedvar1 == -1 || consdata->watchedvar1 != consdata->watchedvar2);

   SCIPdebugMsg(scip, "activating information for bound disjunction constraint <%s>\n", SCIPconsGetName(cons));
   SCIPdebug(consdataPrint(scip, consdata, NULL, TRUE));

   /* catch events on watched variables */
   if( consdata->watchedvar1 != -1 )
   {
      SCIP_CALL( catchEvents(scip, cons, consdata, conshdlrdata->eventhdlr, consdata->watchedvar1,
            &consdata->filterpos1) );
   }
   if( consdata->watchedvar2 != -1 )
   {
      SCIP_CALL( catchEvents(scip, cons, consdata, conshdlrdata->eventhdlr, consdata->watchedvar2,
            &consdata->filterpos2) );
   }

   return SCIP_OKAY;
}


/** constraint deactivation notification method of constraint handler */
static
SCIP_DECL_CONSDEACTIVE(consDeactiveBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSHDLRDATA* conshdlrdata;
   SCIP_CONSDATA* consdata;

   assert(conshdlr != NULL);
   assert(strcmp(SCIPconshdlrGetName(conshdlr), CONSHDLR_NAME) == 0);
   assert(cons != NULL);
   assert(SCIPconsIsTransformed(cons));

   conshdlrdata = SCIPconshdlrGetData(conshdlr);
   assert(conshdlrdata != NULL);
   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);
   assert(consdata->watchedvar1 == -1 || consdata->watchedvar1 != consdata->watchedvar2);

   SCIPdebugMsg(scip, "deactivating information for bound disjunction constraint <%s>\n", SCIPconsGetName(cons));
   SCIPdebug(consdataPrint(scip, consdata, NULL, TRUE));

   /* drop events on watched variables */
   if( consdata->watchedvar1 != -1 )
   {
      assert(consdata->filterpos1 != -1);
      SCIP_CALL( dropEvents(scip, cons, consdata, conshdlrdata->eventhdlr, consdata->watchedvar1, consdata->filterpos1) );
      consdata->watchedvar1 = -1;
   }
   if( consdata->watchedvar2 != -1 )
   {
      assert(consdata->filterpos2 != -1);
      SCIP_CALL( dropEvents(scip, cons, consdata, conshdlrdata->eventhdlr, consdata->watchedvar2, consdata->filterpos2) );
      consdata->watchedvar2 = -1;
   }

   return SCIP_OKAY;
}


/** constraint display method of constraint handler */
static
SCIP_DECL_CONSPRINT(consPrintBounddisjunction)
{  /*lint --e{715}*/

   assert( scip != NULL );
   assert( conshdlr != NULL );
   assert( cons != NULL );

   consdataPrint(scip, SCIPconsGetData(cons), file, FALSE);

   return SCIP_OKAY;
}

/** constraint copying method of constraint handler */
static
SCIP_DECL_CONSCOPY(consCopyBounddisjunction)
{  /*lint --e{715}*/
   SCIP_VAR** sourcevars;
   SCIP_VAR** targetvars;
   SCIP_BOUNDTYPE* boundtypes;
   SCIP_Real* bounds;
   int nvars;
   int v;

   assert(valid != NULL);

   *valid = TRUE;

   /* get source data */
   sourcevars = SCIPgetVarsBounddisjunction(sourcescip, sourcecons);
   nvars = SCIPgetNVarsBounddisjunction(sourcescip, sourcecons);
   boundtypes = SCIPgetBoundtypesBounddisjunction(sourcescip, sourcecons);
   bounds = SCIPgetBoundsBounddisjunction(sourcescip, sourcecons);

   SCIP_CALL( SCIPallocBufferArray(scip, &targetvars, nvars) );

   /* map source variables to active variables of the target SCIP */
   for( v = 0; v < nvars && *valid; ++v )
   {
      SCIP_CALL( SCIPgetVarCopy(sourcescip, scip, sourcevars[v], &targetvars[v], varmap, consmap, global, valid) );
      assert(!(*valid) || targetvars[v] != NULL);
   }

   /* only create the target constraint, if all variables could be copied */
   if( *valid )
   {
      SCIP_CALL( SCIPcreateConsBounddisjunction(scip, cons, name ? name : SCIPconsGetName(sourcecons), nvars, targetvars, boundtypes,
         bounds, initial, separate, enforce, check, propagate, local, modifiable, dynamic, removable, stickingatnode) );
   }

   SCIPfreeBufferArray(scip, &targetvars);

   return SCIP_OKAY;
}

/** constraint parsing method of constraint handler */
static
SCIP_DECL_CONSPARSE(consParseBounddisjunction)
{  /*lint --e{715}*/
   SCIP_BOUNDTYPE* boundtypes;
   SCIP_Real* bounds;
   SCIP_VAR** vars;
   char* endptr;
   int varssize;
   int nvars;

   assert( success != NULL );
   *success = TRUE;

   SCIPdebugMsg(scip, "parse <%s> as bounddisjunction constraint\n", str);

   /* skip white space */
   while( *str != '\0' && isspace((unsigned char)*str) )
      ++str;

   /* check for string "bounddisjunction" */
   if( strncmp(str, "bounddisjunction(", 16) != 0 )
   {
      SCIPverbMessage(scip, SCIP_VERBLEVEL_MINIMAL, NULL, "error during parsing: expected \"bounddisjunction(\" in <%s>.\n", str);
      *success = FALSE;
      return SCIP_OKAY;
   }

   /* skip "bounddisjunction(" */
   str += 17;

   varssize = 100;
   nvars = 0;

   /* allocate buffer array for variables */
   SCIP_CALL( SCIPallocBufferArray(scip, &vars, varssize) );
   SCIP_CALL( SCIPallocBufferArray(scip, &boundtypes, varssize) );
   SCIP_CALL( SCIPallocBufferArray(scip, &bounds, varssize) );

   /* parse string until ")" */
   while( *str != '\0' && *str != ')' )
   {
      SCIP_VAR* var;

      /* parse variable name */ 
      SCIP_CALL( SCIPparseVarName(scip, str, &var, &endptr) );
      str = endptr;

      if( var == NULL )
      {
         SCIPverbMessage(scip, SCIP_VERBLEVEL_MINIMAL, NULL, "Error while parsing variable.\n");
         *success = FALSE;
         goto TERMINATE;
      }

      /* skip white space */
      while( *str != '\0' && isspace((unsigned char)*str) && *str != '>' && *str != '<' )
         ++str;

      /* parse bound type */
      switch( *str )
      {
      case '<':
         boundtypes[nvars] = SCIP_BOUNDTYPE_UPPER;
         break;
      case '>':
         boundtypes[nvars] = SCIP_BOUNDTYPE_LOWER;
         break;
      default:
         SCIPverbMessage(scip, SCIP_VERBLEVEL_MINIMAL, NULL, "variable with name <%s> does not exist\n", SCIPvarGetName(var));
         *success = FALSE;
         goto TERMINATE;
      }

      ++str;
      if( *str != '=' )
      {
         SCIPdebugMsg(scip, "expected '=': %s\n", str);
         *success = FALSE;
         goto TERMINATE;
      }

      /* skip '=' */
      ++str;

      /* skip white space */
      while( *str != '\0' && isspace((unsigned char)*str) )
         ++str;

      /* parse bound value */
      if( !SCIPstrToRealValue(str, &bounds[nvars], &endptr) )
      {
         SCIPverbMessage(scip, SCIP_VERBLEVEL_MINIMAL, NULL, "Syntax error during parsing of the weight: %s\n", str);
         *success = FALSE;
         goto TERMINATE;
      }

      /* skip white space */
      str = endptr;
      while( (*str != '\0' && isspace((unsigned char)*str)) || *str == ',' )
         ++str;

      /* set variable */
      vars[nvars++] = var;

      /* check if the size of the variable array was big enough */
      if( nvars > varssize )
      {
         /* reallocate memory */
         varssize *= 2;
         SCIP_CALL( SCIPreallocBufferArray(scip, &vars, varssize) );
         SCIP_CALL( SCIPreallocBufferArray(scip, &boundtypes, varssize) );
         SCIP_CALL( SCIPreallocBufferArray(scip, &bounds, varssize) );
      }
   }
   /* ignore if the string ended without ")" */

   /* add bounddisjunction */
   if( *success && nvars > 0 )
   {
      SCIP_CALL( SCIPcreateConsBounddisjunction(scip, cons, name, nvars, vars, boundtypes, bounds, 
            initial, separate, enforce, check, propagate, local, modifiable, dynamic, removable, stickingatnode) );
   }

 TERMINATE:
   /* free variable buffer */
   SCIPfreeBufferArray(scip, &bounds);
   SCIPfreeBufferArray(scip, &boundtypes);
   SCIPfreeBufferArray(scip, &vars);

   return SCIP_OKAY;
}

/** constraint method of constraint handler which returns the variables (if possible) */
static
SCIP_DECL_CONSGETVARS(consGetVarsBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSDATA* consdata;

   assert(cons != NULL);

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   if( varssize < consdata->nvars )
      (*success) = FALSE;
   else
   {
      assert(vars != NULL);

      BMScopyMemoryArray(vars, consdata->vars, consdata->nvars);
      (*success) = TRUE;
   }

   return SCIP_OKAY;
}

/** constraint method of constraint handler which returns the number of variables (if possible) */
static
SCIP_DECL_CONSGETNVARS(consGetNVarsBounddisjunction)
{  /*lint --e{715}*/
   SCIP_CONSDATA* consdata;

   assert(cons != NULL);

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   (*nvars) = consdata->nvars;
   (*success) = TRUE;

   return SCIP_OKAY;
}

/**@} */

/**@name Callback methods of event handler
 *
 */

static
SCIP_DECL_EVENTEXEC(eventExecBounddisjunction)
{  /*lint --e{715}*/
   assert(eventhdlr != NULL);
   assert(eventdata != NULL);
   assert(strcmp(SCIPeventhdlrGetName(eventhdlr), EVENTHDLR_NAME) == 0);
   assert(event != NULL);

   /*SCIPdebugMsg(scip, "exec method of event handler for bound disjunction constraints\n");*/

   assert(SCIPconsGetData((SCIP_CONS*)eventdata) != NULL);
   assert(SCIPconsIsActive((SCIP_CONS*)eventdata) || SCIPconsIsUpdatedeactivate((SCIP_CONS*)eventdata));

   if( (SCIPeventGetType(event) & SCIP_EVENTTYPE_BOUNDRELAXED) != 0 )
   {
      SCIP_CALL( SCIPenableCons(scip, (SCIP_CONS*)eventdata) );
   }
   else
      assert((SCIPeventGetType(event) & SCIP_EVENTTYPE_BOUNDTIGHTENED) != 0);

   SCIP_CALL( SCIPenableConsPropagation(scip, (SCIP_CONS*)eventdata) );

   return SCIP_OKAY;
}

/**@} */

/**@name Callback methods of conflict handler
 *
 * @{
 */

/** conflict handler data struct */
struct SCIP_ConflicthdlrData
{
   SCIP_Real             continuousfrac;     /**< maximal percantage of continuous variables within a conflict */
};

/** conflict processing method of conflict handler (called when conflict was found) */
static
SCIP_DECL_CONFLICTEXEC(conflictExecBounddisjunction)
{  /*lint --e{715}*/
   SCIP_VAR** vars;
   SCIP_CONFLICTHDLRDATA* conflicthdlrdata;
   SCIP_BOUNDTYPE* boundtypes;
   SCIP_Real* bounds;
   SCIP_CONS* cons;
   char consname[SCIP_MAXSTRLEN];
   int nliterals;
   int ncontinuous;
   int i;

   assert(conflicthdlr != NULL);
   assert(strcmp(SCIPconflicthdlrGetName(conflicthdlr), CONFLICTHDLR_NAME) == 0);
   assert(bdchginfos != NULL || nbdchginfos == 0);
   assert(result != NULL);

   /* don't process already resolved conflicts */
   if( resolved )
   {
      *result = SCIP_DIDNOTRUN;
      return SCIP_OKAY;
   }

   conflicthdlrdata = SCIPconflicthdlrGetData(conflicthdlr);
   assert(conflicthdlrdata != NULL);

   *result = SCIP_DIDNOTFIND;
   ncontinuous = 0;

   /* create array of variables, boundtypes, and bound values in conflict constraint */
   SCIP_CALL( SCIPallocBufferArray(scip, &vars, nbdchginfos) );
   SCIP_CALL( SCIPallocBufferArray(scip, &boundtypes, nbdchginfos) );
   SCIP_CALL( SCIPallocBufferArray(scip, &bounds, nbdchginfos) );

   nliterals = 0;

   for( i = 0; i < nbdchginfos; ++i )
   {
      SCIP_VAR* var;
      SCIP_Real bound;
      SCIP_BOUNDTYPE boundtype;
      int j;

      assert(bdchginfos != NULL);

      var = SCIPbdchginfoGetVar(bdchginfos[i]);
      assert(var != NULL);

      boundtype = SCIPboundtypeOpposite(SCIPbdchginfoGetBoundtype(bdchginfos[i]));
      bound = relaxedbds[i];

      /* for continuous variables, we can only use the relaxed version of the bounds negation: !(x <= u) -> x >= u */
      if( SCIPvarIsIntegral(var) )
         bound += (boundtype == SCIP_BOUNDTYPE_LOWER ? +1.0 : -1.0);

      /* check whether we have seen the variable before */
      for( j = nliterals-1; j >= 0; --j )
      {
         if( vars[j] != var )
            continue;

         /* check whether both literals contribute with the same bound type */
         if( boundtypes[j] == boundtype )
         {
            /* check whether the lower bound can be relaxed */
            if( boundtype == SCIP_BOUNDTYPE_LOWER && SCIPisLT(scip, bound, bounds[j]) )
            {
               SCIPdebugMsg(scip, "relax lower bound of variable <%s> from %g to %g in bounddisjunction conflict\n",
                  SCIPvarGetName(var), bounds[j], bound);
               bounds[j] = bound;
            }
            /* check whether the upper bound can be relaxed */
            else if( boundtype == SCIP_BOUNDTYPE_UPPER && SCIPisGT(scip, bound, bounds[j]) )
            {
               SCIPdebugMsg(scip, "relax upper bound of variable <%s> from %g to %g in bounddisjunction conflict\n",
                  SCIPvarGetName(var), bounds[j], bound);
               bounds[j] = bound;
            }

            continue;
         }
         /* check whether the bounds are overlapping */
         else if( isOverlapping(scip, var, boundtype, bound, boundtypes[j], bounds[j]) )
         {
            /* the conflict is redundant -> discard the conflict constraint */
            SCIPdebugMsg(scip, "redundant bounddisjunction conflict due to overlapping\n");
            goto DISCARDCONFLICT;
         }
      }

      vars[nliterals] = var;
      boundtypes[nliterals] = boundtype;
      bounds[nliterals] = bound;

      /* check if the relaxed bound is really a relaxed bound */
      assert(SCIPbdchginfoGetBoundtype(bdchginfos[i]) == SCIP_BOUNDTYPE_LOWER || SCIPisGE(scip, relaxedbds[i], SCIPbdchginfoGetNewbound(bdchginfos[i])));
      assert(SCIPbdchginfoGetBoundtype(bdchginfos[i]) == SCIP_BOUNDTYPE_UPPER || SCIPisLE(scip, relaxedbds[i], SCIPbdchginfoGetNewbound(bdchginfos[i])));

      /* for continuous variables, we can only use the relaxed version of the bounds negation: !(x <= u) -> x >= u */
      if( !SCIPvarIsIntegral(vars[nliterals]) )
      {
         if( (boundtypes[i] == SCIP_BOUNDTYPE_LOWER && SCIPisFeasEQ(scip, SCIPvarGetLbGlobal(var), bounds[nliterals]))
            || (boundtypes[i] == SCIP_BOUNDTYPE_UPPER && SCIPisFeasEQ(scip, SCIPvarGetUbGlobal(var), bounds[nliterals])) )
         {
            /* the literal is satisfied in global bounds (may happen due to weak "negation" of continuous variables)
             * -> discard the conflict constraint
             */
            SCIPdebugMsg(scip, "redundant bounddisjunction conflict due to globally fulfilled literal\n");
            goto DISCARDCONFLICT;
         }
         else
            ncontinuous++;
      }

      nliterals++;
   }

   /* create a constraint out of the conflict set */
   if( i == nbdchginfos && ncontinuous < conflicthdlrdata->continuousfrac * nbdchginfos + 0.5 )
   {
      (void) SCIPsnprintf(consname, SCIP_MAXSTRLEN, "cf%d_%" SCIP_LONGINT_FORMAT, SCIPgetNRuns(scip), SCIPgetNConflictConssApplied(scip));
      SCIP_CALL( SCIPcreateConsBounddisjunction(scip, &cons, consname, nliterals, vars, boundtypes, bounds,
            FALSE, FALSE, FALSE, FALSE, TRUE, local, FALSE, dynamic, removable, FALSE) );

      /* add conflict to SCIP */
      SCIP_CALL( SCIPaddConflict(scip, node, cons, validnode, conftype, cutoffinvolved) );
      SCIPdebugMsg(scip, "added conflict\n");
      *result = SCIP_CONSADDED;
   }

  DISCARDCONFLICT:
   /* free temporary memory */
   SCIPfreeBufferArray(scip, &bounds);
   SCIPfreeBufferArray(scip, &boundtypes);
   SCIPfreeBufferArray(scip, &vars);

   return SCIP_OKAY;
}

/** free method of conflict handler */
static
SCIP_DECL_CONFLICTFREE(conflictFreeBounddisjunction)
{
   SCIP_CONFLICTHDLRDATA* conflicthdlrdata;

   assert(conflicthdlr != NULL);

   /* get conflict handler data */
   conflicthdlrdata = SCIPconflicthdlrGetData(conflicthdlr);
   assert(conflicthdlrdata != NULL);

   /* free conflict handler structure */
   SCIPfreeBlockMemory(scip, &conflicthdlrdata);

   return SCIP_OKAY;
}

/**@} */

/**@name Interface methods
 *
 * @{
 */

/** creates the handler for bound disjunction constraints and includes it in SCIP */
SCIP_RETCODE SCIPincludeConshdlrBounddisjunction(
   SCIP*                 scip                /**< SCIP data structure */
   )
{
   SCIP_CONSHDLRDATA* conshdlrdata;
   SCIP_CONFLICTHDLRDATA* conflicthdlrdata;
   SCIP_CONFLICTHDLR* conflicthdlr;
   SCIP_CONSHDLR* conshdlr;
   SCIP_EVENTHDLR* eventhdlr;

   /* create event handler for events on watched variables */
   SCIP_CALL( SCIPincludeEventhdlrBasic(scip, &eventhdlr, EVENTHDLR_NAME, EVENTHDLR_DESC,
         eventExecBounddisjunction, NULL) );

   /* allocate memory for conflict handler data */
   SCIP_CALL( SCIPallocBlockMemory(scip, &conflicthdlrdata) );

   /* create conflict handler parameter */
   SCIP_CALL( SCIPaddRealParam(scip,
         "conflict/" CONSHDLR_NAME "/continuousfrac", "maximal percantage of continuous variables within a conflict",
         &conflicthdlrdata->continuousfrac, FALSE, DEFAULT_CONTINUOUSFRAC, 0.0, 1.0, NULL, NULL) );

   /* create conflict handler for bound disjunction constraints */
   SCIP_CALL( SCIPincludeConflicthdlrBasic(scip, &conflicthdlr, CONFLICTHDLR_NAME, CONFLICTHDLR_DESC, CONFLICTHDLR_PRIORITY,
         conflictExecBounddisjunction, conflicthdlrdata) );

   SCIP_CALL( SCIPsetConflicthdlrFree(scip, conflicthdlr, conflictFreeBounddisjunction) );

   /* create constraint handler data */
   SCIP_CALL( conshdlrdataCreate(scip, &conshdlrdata, eventhdlr) );

   /* include constraint handler */
   SCIP_CALL( SCIPincludeConshdlrBasic(scip, &conshdlr, CONSHDLR_NAME, CONSHDLR_DESC,
         CONSHDLR_ENFOPRIORITY, CONSHDLR_CHECKPRIORITY, CONSHDLR_EAGERFREQ, CONSHDLR_NEEDSCONS,
         consEnfolpBounddisjunction, consEnfopsBounddisjunction, consCheckBounddisjunction, consLockBounddisjunction,
         conshdlrdata) );

   assert(conshdlr != NULL);

   /* set non-fundamental callbacks via specific setter functions */
   SCIP_CALL( SCIPsetConshdlrActive(scip, conshdlr, consActiveBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrCopy(scip, conshdlr, conshdlrCopyBounddisjunction, consCopyBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrDeactive(scip, conshdlr, consDeactiveBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrDelete(scip, conshdlr, consDeleteBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrExitpre(scip, conshdlr, consExitpreBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrFree(scip, conshdlr, consFreeBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrGetVars(scip, conshdlr, consGetVarsBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrGetNVars(scip, conshdlr, consGetNVarsBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrParse(scip, conshdlr, consParseBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrPresol(scip, conshdlr, consPresolBounddisjunction, CONSHDLR_MAXPREROUNDS,
         CONSHDLR_PRESOLTIMING) );
   SCIP_CALL( SCIPsetConshdlrPrint(scip, conshdlr, consPrintBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrProp(scip, conshdlr, consPropBounddisjunction, CONSHDLR_PROPFREQ, CONSHDLR_DELAYPROP,
         CONSHDLR_PROP_TIMING) );
   SCIP_CALL( SCIPsetConshdlrResprop(scip, conshdlr, consRespropBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrTrans(scip, conshdlr, consTransBounddisjunction) );
   SCIP_CALL( SCIPsetConshdlrEnforelax(scip, conshdlr, consEnforelaxBounddisjunction) );

   /* register upgrade of quadratic complementarity constraints in cons_quadratic */
   if( SCIPfindConshdlr(scip, "quadratic") )
   {
      SCIP_CALL( SCIPincludeQuadconsUpgrade(scip, upgradeConsQuadratic, QUADCONSUPGD_PRIORITY, TRUE, CONSHDLR_NAME) );
   }

   return SCIP_OKAY;
}


/** creates and captures a bound disjunction constraint
 *
 *  @note the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
 */
SCIP_RETCODE SCIPcreateConsBounddisjunction(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS**           cons,               /**< pointer to hold the created constraint */
   const char*           name,               /**< name of constraint */
   int                   nvars,              /**< number of variables in the constraint */
   SCIP_VAR**            vars,               /**< variables of the literals in the constraint */
   SCIP_BOUNDTYPE*       boundtypes,         /**< types of bounds of the literals (lower or upper bounds) */
   SCIP_Real*            bounds,             /**< bounds of the literals */
   SCIP_Bool             initial,            /**< should the LP relaxation of constraint be in the initial LP?
                                              *   Usually set to TRUE. Set to FALSE for 'lazy constraints'. */
   SCIP_Bool             separate,           /**< should the constraint be separated during LP processing?
                                              *   Usually set to TRUE. */
   SCIP_Bool             enforce,            /**< should the constraint be enforced during node processing?
                                              *   TRUE for model constraints, FALSE for additional, redundant constraints. */
   SCIP_Bool             check,              /**< should the constraint be checked for feasibility?
                                              *   TRUE for model constraints, FALSE for additional, redundant constraints. */
   SCIP_Bool             propagate,          /**< should the constraint be propagated during node processing?
                                              *   Usually set to TRUE. */
   SCIP_Bool             local,              /**< is constraint only valid locally?
                                              *   Usually set to FALSE. Has to be set to TRUE, e.g., for branching constraints. */
   SCIP_Bool             modifiable,         /**< is constraint modifiable (subject to column generation)?
                                              *   Usually set to FALSE. In column generation applications, set to TRUE if pricing
                                              *   adds coefficients to this constraint. */
   SCIP_Bool             dynamic,            /**< is constraint subject to aging?
                                              *   Usually set to FALSE. Set to TRUE for own cuts which
                                              *   are separated as constraints. */
   SCIP_Bool             removable,          /**< should the relaxation be removed from the LP due to aging or cleanup?
                                              *   Usually set to FALSE. Set to TRUE for 'lazy constraints' and 'user cuts'. */
   SCIP_Bool             stickingatnode      /**< should the constraint always be kept at the node where it was added, even
                                              *   if it may be moved to a more global node?
                                              *   Usually set to FALSE. Set to TRUE to for constraints that represent node data. */
   )
{
   SCIP_CONSHDLR* conshdlr;
   SCIP_CONSDATA* consdata;

   assert(scip != NULL);

   /* find the bounddisjunction constraint handler */
   conshdlr = SCIPfindConshdlr(scip, CONSHDLR_NAME);
   if( conshdlr == NULL )
   {
      SCIPerrorMessage("bound disjunction constraint handler not found\n");
      return SCIP_PLUGINNOTFOUND;
   }

#ifndef NDEBUG
   {
      int v1;
      /* ensure that the given data neither contains overlapping nor redundant literals */
      for( v1 = 0; v1 < nvars; v1++ )
      {
         int v2;
         for( v2 = v1+1; v2 < nvars; v2++ )
         {
            assert(vars[v1] != vars[v2] || (SCIPboundtypeOpposite(boundtypes[v1]) == boundtypes[v2]
                  && !isOverlapping(scip, vars[v1], boundtypes[v1], bounds[v1], boundtypes[v2], bounds[v2])));
         }
      }
   }
#endif

   /* create the constraint specific data */
   SCIP_CALL( consdataCreate(scip, &consdata, nvars, vars, boundtypes, bounds) );

   /* create constraint */
   SCIP_CALL( SCIPcreateCons(scip, cons, name, conshdlr, consdata, initial, separate, enforce, check, propagate,
         local, modifiable, dynamic, removable, stickingatnode) );

   return SCIP_OKAY;
}

/** creates and captures a bound disjunction constraint
 *  in its most basic version, i. e., all constraint flags are set to their basic value as explained for the
 *  method SCIPcreateConsBounddisjunction(); all flags can be set via SCIPsetConsFLAGNAME-methods in scip.h
 *
 *  @see SCIPcreateConsBounddisjunction() for information about the basic constraint flag configuration
 *
 *  @note the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
 */
SCIP_RETCODE SCIPcreateConsBasicBounddisjunction(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS**           cons,               /**< pointer to hold the created constraint */
   const char*           name,               /**< name of constraint */
   int                   nvars,              /**< number of variables in the constraint */
   SCIP_VAR**            vars,               /**< variables of the literals in the constraint */
   SCIP_BOUNDTYPE*       boundtypes,         /**< types of bounds of the literals (lower or upper bounds) */
   SCIP_Real*            bounds              /**< bounds of the literals */
   )
{
   assert(scip != NULL);

   SCIP_CALL( SCIPcreateConsBounddisjunction(scip, cons, name, nvars, vars, boundtypes, bounds,
         TRUE, TRUE, TRUE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE) );

   return SCIP_OKAY;
}

/** gets number of variables in bound disjunction constraint */
int SCIPgetNVarsBounddisjunction(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint data */
   )
{
   SCIP_CONSDATA* consdata;

   if( strcmp(SCIPconshdlrGetName(SCIPconsGetHdlr(cons)), CONSHDLR_NAME) != 0 )
   {
      SCIPerrorMessage("constraint is not a bound disjunction constraint\n");
      SCIPABORT();
      return 0; /*lint !e527*/
   }

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   return consdata->nvars;
}

/** gets array of variables in bound disjunction constraint */
SCIP_VAR** SCIPgetVarsBounddisjunction(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint data */
   )
{
   SCIP_CONSDATA* consdata;

   if( strcmp(SCIPconshdlrGetName(SCIPconsGetHdlr(cons)), CONSHDLR_NAME) != 0 )
   {
      SCIPerrorMessage("constraint is not a bound disjunction constraint\n");
      SCIPABORT();
      return NULL; /*lint !e527*/
   }

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   return consdata->vars;
}

/** gets array of bound types in bound disjunction constraint */
SCIP_BOUNDTYPE* SCIPgetBoundtypesBounddisjunction(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint data */
   )
{
   SCIP_CONSDATA* consdata;

   if( strcmp(SCIPconshdlrGetName(SCIPconsGetHdlr(cons)), CONSHDLR_NAME) != 0 )
   {
      SCIPerrorMessage("constraint is not a bound disjunction constraint\n");
      SCIPABORT();
      return NULL; /*lint !e527*/
   }

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   return consdata->boundtypes;
}

/** gets array of bounds in bound disjunction constraint */
SCIP_Real* SCIPgetBoundsBounddisjunction(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_CONS*            cons                /**< constraint data */
   )
{
   SCIP_CONSDATA* consdata;

   if( strcmp(SCIPconshdlrGetName(SCIPconsGetHdlr(cons)), CONSHDLR_NAME) != 0 )
   {
      SCIPerrorMessage("constraint is not a bound disjunction constraint\n");
      SCIPABORT();
      return NULL; /*lint !e527*/
   }

   consdata = SCIPconsGetData(cons);
   assert(consdata != NULL);

   return consdata->bounds;
}

/**@} */