Example #1
0
/** checks if a given branching candidate is better than a previous one and updates the best branching candidate accordingly */
static
SCIP_RETCODE updateBestCandidate(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_BRANCHRULEDATA*  branchruledata,     /**< branching rule data */
   SCIP_VAR**            bestvar,            /**< best branching candidate */
   SCIP_Real*            bestbrpoint,        /**< branching point for best branching candidate */
   SCIP_Real*            bestscore,          /**< score of best branching candidate */
   SCIP_VAR*             cand,               /**< branching candidate to consider */
   SCIP_Real             candscoremin,       /**< minimal score of branching candidate */
   SCIP_Real             candscoremax,       /**< maximal score of branching candidate */
   SCIP_Real             candscoresum,       /**< sum of scores of branching candidate */
   SCIP_Real             candsol             /**< proposed branching point of branching candidate */          
)
{
   SCIP_Real candbrpoint;
   SCIP_Real branchscore;

   SCIP_Real deltaminus;
   SCIP_Real deltaplus;

   SCIP_Real pscostdown;
   SCIP_Real pscostup;
   
   char strategy;

   assert(scip != NULL);
   assert(branchruledata != NULL);
   assert(bestvar != NULL);
   assert(bestbrpoint != NULL);
   assert(bestscore != NULL);
   assert(cand != NULL);

   /* a branching variable candidate should either be an active problem variable or a multi-aggregated variable */
   assert(SCIPvarIsActive(SCIPvarGetProbvar(cand)) ||
      SCIPvarGetStatus(SCIPvarGetProbvar(cand)) == SCIP_VARSTATUS_MULTAGGR);
   
   if( SCIPvarGetStatus(SCIPvarGetProbvar(cand)) == SCIP_VARSTATUS_MULTAGGR )
   {
      /* for a multi-aggregated variable, we call updateBestCandidate function recursively with all variables in the multi-aggregation */
      SCIP_VAR** multvars;
      int nmultvars;
      int i;
      SCIP_Bool success;
      SCIP_Real multvarlb;
      SCIP_Real multvarub;

      cand = SCIPvarGetProbvar(cand);
      multvars = SCIPvarGetMultaggrVars(cand);
      nmultvars = SCIPvarGetMultaggrNVars(cand);

      /* if we have a candidate branching point, then first register only aggregation variables
       * for which we can compute a corresponding branching point too (see also comments below)
       * if this fails, then register all (unfixed) aggregation variables, thereby forgetting about candsol
       */
      success = FALSE;
      if( candsol != SCIP_INVALID ) /*lint !e777*/
      {
         SCIP_Real* multscalars;
         SCIP_Real minact;
         SCIP_Real maxact;
         SCIP_Real aggrvarsol;
         SCIP_Real aggrvarsol1;
         SCIP_Real aggrvarsol2;

         multscalars = SCIPvarGetMultaggrScalars(cand);

         /* for computing the branching point, we need the current bounds of the multi-aggregated variable */
         minact = SCIPcomputeVarLbLocal(scip, cand);
         maxact = SCIPcomputeVarUbLocal(scip, cand);

         for( i = 0; i < nmultvars; ++i )
         {
            /* skip fixed variables */
            multvarlb = SCIPcomputeVarLbLocal(scip, multvars[i]);
            multvarub = SCIPcomputeVarUbLocal(scip, multvars[i]);
            if( SCIPisEQ(scip, multvarlb, multvarub) )
               continue;

            assert(multscalars != NULL);
            assert(multscalars[i] != 0.0);

            /* we cannot ensure that both the upper bound in the left node and the lower bound in the right node
             * will be candsol by a clever choice for the branching point of multvars[i],
             * but we can try to ensure that at least one of them will be at candsol
             */
            if( multscalars[i] > 0.0 )
            {
               /*    cand >= candsol
                * if multvars[i] >= (candsol - (maxact - multscalars[i] * ub(multvars[i]))) / multscalars[i]
                *                 = (candsol - maxact) / multscalars[i] + ub(multvars[i])
                */
               aggrvarsol1 = (candsol - maxact) / multscalars[i] + multvarub;

               /*     cand <= candsol
                * if multvars[i] <= (candsol - (minact - multscalar[i] * lb(multvars[i]))) / multscalars[i]
                *                 = (candsol - minact) / multscalars[i] + lb(multvars[i])
                */
               aggrvarsol2 = (candsol - minact) / multscalars[i] + multvarlb;
            }
            else
            {
               /*    cand >= candsol
                * if multvars[i] <= (candsol - (maxact - multscalars[i] * lb(multvars[i]))) / multscalars[i]
                *                 = (candsol - maxact) / multscalars[i] + lb(multvars[i])
                */
               aggrvarsol2 = (candsol - maxact) / multscalars[i] + multvarlb;

               /*    cand <= candsol
                * if multvars[i] >= (candsol - (minact - multscalar[i] * ub(multvars[i]))) / multscalars[i]
                *                 = (candsol - minact) / multscalars[i] + ub(multvars[i])
                */
               aggrvarsol1 = (candsol - minact) / multscalars[i] + multvarub;
            }

            /* by the above choice, aggrvarsol1 <= ub(multvars[i]) and aggrvarsol2 >= lb(multvars[i])
             * if aggrvarsol1 <= lb(multvars[i]) or aggrvarsol2 >= ub(multvars[i]), then choose the other one
             * if both are out of bounds, then give up
             * if both are inside bounds, then choose the one closer to 0.0 (someone has better idea???)
             */
            if( SCIPisFeasLE(scip, aggrvarsol1, multvarlb) )
            {
               if( SCIPisFeasGE(scip, aggrvarsol2, multvarub) )
                  continue;
               else
                  aggrvarsol = aggrvarsol2;
            }
            else
            {
               if( SCIPisFeasGE(scip, aggrvarsol2, multvarub) )
                  aggrvarsol = aggrvarsol1;
               else
                  aggrvarsol = REALABS(aggrvarsol1) < REALABS(aggrvarsol2) ? aggrvarsol1 : aggrvarsol2;
            }
            success = TRUE;

            SCIP_CALL( updateBestCandidate(scip, branchruledata, bestvar, bestbrpoint, bestscore,
                  multvars[i], candscoremin, candscoremax, candscoresum, aggrvarsol) );
         }
      }

      if( !success )
         for( i = 0; i < nmultvars; ++i )
         {
            /* skip fixed variables */
            multvarlb = SCIPcomputeVarLbLocal(scip, multvars[i]);
            multvarub = SCIPcomputeVarUbLocal(scip, multvars[i]);
            if( SCIPisEQ(scip, multvarlb, multvarub) )
               continue;

            SCIP_CALL( updateBestCandidate(scip, branchruledata, bestvar, bestbrpoint, bestscore,
               multvars[i], candscoremin, candscoremax, candscoresum, SCIP_INVALID) );
         }

      assert(*bestvar != NULL); /* if all variables were fixed, something is strange */
      
      return SCIP_OKAY;
   }
   
   /* select branching point for this variable */
   candbrpoint = SCIPgetBranchingPoint(scip, cand, candsol);
   assert(candbrpoint >= SCIPvarGetLbLocal(cand));
   assert(candbrpoint <= SCIPvarGetUbLocal(cand));

   /* we cannot branch on a huge value for a discrete variable, because we simply cannot enumerate such huge integer values in floating point
    * arithmetics
    */
   if( SCIPvarGetType(cand) != SCIP_VARTYPE_CONTINUOUS && (SCIPisHugeValue(scip, candbrpoint) || SCIPisHugeValue(scip, -candbrpoint)) )
      return SCIP_OKAY;

   assert(SCIPvarGetType(cand) == SCIP_VARTYPE_CONTINUOUS || !SCIPisIntegral(scip, candbrpoint));

   if( SCIPvarGetType(cand) == SCIP_VARTYPE_CONTINUOUS )
      strategy = (branchruledata->strategy == 'u' ? branchruledata->updatestrategy : branchruledata->strategy);
   else
      strategy = (branchruledata->strategy == 'u' ? 'l' : branchruledata->strategy);

   switch( strategy )
   {
   case 'l':
      if( SCIPisInfinity(scip,  SCIPgetSolVal(scip, NULL, cand)) || SCIPgetSolVal(scip, NULL, cand) <= SCIPadjustedVarUb(scip, cand, candbrpoint) )
         deltaminus = 0.0;
      else
         deltaminus = SCIPgetSolVal(scip, NULL, cand) - SCIPadjustedVarUb(scip, cand, candbrpoint);
      if( SCIPisInfinity(scip, -SCIPgetSolVal(scip, NULL, cand)) || SCIPgetSolVal(scip, NULL, cand) >= SCIPadjustedVarLb(scip, cand, candbrpoint) )
         deltaplus = 0.0;
      else
         deltaplus = SCIPadjustedVarLb(scip, cand, candbrpoint) - SCIPgetSolVal(scip, NULL, cand);
      break;

   case 'd':
      if( SCIPisInfinity(scip, -SCIPvarGetLbLocal(cand)) )
         deltaminus = SCIPisInfinity(scip, candscoremax) ? SCIPinfinity(scip) : WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum);
      else
         deltaminus = SCIPadjustedVarUb(scip, cand, candbrpoint) - SCIPvarGetLbLocal(cand);

      if( SCIPisInfinity(scip,  SCIPvarGetUbLocal(cand)) )
         deltaplus = SCIPisInfinity(scip, candscoremax) ? SCIPinfinity(scip) : WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum);
      else
         deltaplus = SCIPvarGetUbLocal(cand) - SCIPadjustedVarLb(scip, cand, candbrpoint);
      break;
      
   case 's':
      if( SCIPisInfinity(scip, -SCIPvarGetLbLocal(cand)) )
         deltaplus = SCIPisInfinity(scip, candscoremax) ? SCIPinfinity(scip) : WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum);
      else
         deltaplus = SCIPadjustedVarUb(scip, cand, candbrpoint) - SCIPvarGetLbLocal(cand);

      if( SCIPisInfinity(scip,  SCIPvarGetUbLocal(cand)) )
         deltaminus = SCIPisInfinity(scip, candscoremax) ? SCIPinfinity(scip) : WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum);
      else
         deltaminus = SCIPvarGetUbLocal(cand) - SCIPadjustedVarLb(scip, cand, candbrpoint);
      break;

   case 'v':
      deltaplus = SCIPisInfinity(scip, candscoremax) ? SCIPinfinity(scip) : WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum);
      deltaminus = deltaplus;
      break;

   default :
      SCIPerrorMessage("branching strategy %c unknown\n", strategy);
      SCIPABORT();
      return SCIP_INVALIDDATA;  /*lint !e527*/
   }

   if( SCIPisInfinity(scip, deltaminus) || SCIPisInfinity(scip, deltaplus) )
   {
      branchscore = SCIPinfinity(scip);
   }
   else
   {
      pscostdown  = SCIPgetVarPseudocostVal(scip, cand, -deltaminus);
      pscostup    = SCIPgetVarPseudocostVal(scip, cand,  deltaplus);
      branchscore = SCIPgetBranchScore(scip, cand, pscostdown, pscostup);
      assert(!SCIPisNegative(scip, branchscore));
   }
   SCIPdebugMessage("branching score variable <%s>[%g,%g] = %g; wscore = %g; type=%d bestbrscore=%g\n",
      SCIPvarGetName(cand), SCIPvarGetLbLocal(cand), SCIPvarGetUbLocal(cand), branchscore, WEIGHTEDSCORING(branchruledata, candscoremin, candscoremax, candscoresum),
      SCIPvarGetType(cand), *bestscore);

   if( SCIPisInfinity(scip, branchscore) )
      branchscore = 0.9*SCIPinfinity(scip);
   
   if( SCIPisSumGT(scip, branchscore, *bestscore) )
   {
      (*bestscore)   = branchscore;
      (*bestvar)     = cand;
      (*bestbrpoint) = candbrpoint;
   }
   else if( SCIPisSumEQ(scip, branchscore, *bestscore)
      && !(SCIPisInfinity(scip, -SCIPvarGetLbLocal(*bestvar)) && SCIPisInfinity(scip, SCIPvarGetUbLocal(*bestvar))) )
   {
      /* if best candidate so far is not unbounded to both sides, maybe take new candidate */
      if( (SCIPisInfinity(scip, -SCIPvarGetLbLocal(cand))     || SCIPisInfinity(scip, SCIPvarGetUbLocal(cand))) &&
          (SCIPisInfinity(scip, -SCIPvarGetLbLocal(*bestvar)) || SCIPisInfinity(scip, SCIPvarGetUbLocal(*bestvar))) )
      { 
         /* if both variables are unbounded but one of them is bounded on one side, take the one with the larger bound on this side (hope that this avoids branching on always the same variable) */
         if( SCIPvarGetUbLocal(cand) > SCIPvarGetUbLocal(*bestvar) || SCIPvarGetLbLocal(cand) < SCIPvarGetLbLocal(*bestvar) )
         {
            (*bestscore)   = branchscore;
            (*bestvar)     = cand;
            (*bestbrpoint) = candbrpoint;
         }
      }
      else if( SCIPvarGetType(*bestvar) == SCIPvarGetType(cand) )
      { 
         /* if both have the same type, take the one with larger diameter */
         if( SCIPvarGetUbLocal(*bestvar) - SCIPvarGetLbLocal(*bestvar) < SCIPvarGetUbLocal(cand) - SCIPvarGetLbLocal(cand) )
         {
            (*bestscore)   = branchscore;
            (*bestvar)     = cand;
            (*bestbrpoint) = candbrpoint;
         }
      }
      else if( SCIPvarGetType(*bestvar) > SCIPvarGetType(cand) )
      { 
         /* take the one with better type ("more discrete") */
         (*bestscore)   = branchscore;
         (*bestvar)     = cand;
         (*bestbrpoint) = candbrpoint;
      }
   }

   return SCIP_OKAY;
}
Example #2
0
/** branching execution method for external candidates */
static
SCIP_DECL_BRANCHEXECEXT(branchExecextRandom)
{  /*lint --e{715}*/
   SCIP_BRANCHRULEDATA* branchruledata;
   SCIP_VAR** externcands;
   SCIP_Real* externcandssol;
   int nprioexterncands;
   SCIP_VAR* bestcand;
   SCIP_Real bestcandsol;
   SCIP_Real brpoint;
   SCIP_NODE* downchild;
   SCIP_NODE* eqchild;
   SCIP_NODE* upchild;

   assert(branchrule != NULL);
   assert(strcmp(SCIPbranchruleGetName(branchrule), BRANCHRULE_NAME) == 0);
   assert(scip != NULL);
   assert(result != NULL);

   SCIPdebugMessage("Execrel method of random branching\n");

   branchruledata = SCIPbranchruleGetData(branchrule);
   assert(branchruledata != NULL);

   bestcand = NULL;
   bestcandsol = 0.0;

   /* get branching candidates */
   SCIP_CALL( SCIPgetExternBranchCands(scip, &externcands, &externcandssol, NULL, NULL, &nprioexterncands, NULL, NULL, NULL) );
   assert(nprioexterncands > 0);

   /* get random branching candidate
    *
    * since variables can occur several times in the list of candidates, variables that have been added more often have
    * a higher probability to be chosen for branching
    */
   getRandomVariable(scip, externcands, externcandssol, nprioexterncands, &bestcand, &bestcandsol, &branchruledata->seed);

   if( bestcand == NULL )
   {
      SCIPerrorMessage("branchExecrelRandom failed to select a branching variable from %d candidates\n", nprioexterncands);
      *result = SCIP_DIDNOTRUN;
      return SCIP_OKAY;
   }

   brpoint = SCIPgetBranchingPoint(scip, bestcand, bestcandsol);

   SCIPdebugMessage(" -> %d candidates, selected variable <%s> with solution value %g, branching point=%g\n",
      nprioexterncands, SCIPvarGetName(bestcand), bestcandsol, brpoint);

   SCIP_CALL( SCIPbranchVarVal(scip, bestcand, brpoint, &downchild, &eqchild, &upchild) );

   if( downchild != NULL || eqchild != NULL || upchild != NULL )
   {
      *result = SCIP_BRANCHED;
   }
   else
   {
      /* if there are no children, then variable should have been fixed by SCIPbranchVarVal */
      assert(SCIPisEQ(scip, SCIPvarGetLbLocal(bestcand), SCIPvarGetUbLocal(bestcand)));
      *result = SCIP_REDUCEDDOM;
   }

   return SCIP_OKAY;
}
Example #3
0
/** branching execution method for external candidates */
static
SCIP_DECL_BRANCHEXECEXT(branchExecextLeastinf)
{  /*lint --e{715}*/
   SCIP_VAR** externcands;
   SCIP_Real* externcandssol;
   SCIP_Real* externcandsscore;
   int nexterncands;
   SCIP_VAR* bestcand;
   SCIP_Real bestscore;
   SCIP_Real bestobj;
   SCIP_Real bestsol;
   SCIP_Real brpoint;
   int i;
   SCIP_NODE* downchild;
   SCIP_NODE* eqchild;
   SCIP_NODE* upchild;

   assert(branchrule != NULL);
   assert(strcmp(SCIPbranchruleGetName(branchrule), BRANCHRULE_NAME) == 0);
   assert(scip != NULL);
   assert(result != NULL);

   SCIPdebugMessage("Execext method of leastinf branching\n");

   /* get branching candidates */
   SCIP_CALL( SCIPgetExternBranchCands(scip, &externcands, &externcandssol, &externcandsscore, NULL, &nexterncands, NULL, NULL, NULL) );
   assert(nexterncands > 0);

   /* search the least infeasible candidate */
   bestscore = SCIPinfinity(scip);
   bestobj  = 0.0;
   bestcand = NULL;
   bestsol = SCIP_INVALID;
   for( i = 0; i < nexterncands; ++i )
   {
      updateBestCandidate(scip, &bestcand, &bestscore, &bestobj, &bestsol, externcands[i], externcandsscore[i], externcandssol[i]);
   }

   if( bestcand == NULL )
   {
      SCIPerrorMessage("branchExecextLeastinf failed to select a branching variable from %d candidates\n", nexterncands);
      *result = SCIP_DIDNOTRUN;
      return SCIP_OKAY;
   }

   brpoint = SCIPgetBranchingPoint(scip, bestcand, bestsol);

   SCIPdebugMessage(" -> %d candidates, selected variable <%s> (infeas=%g, obj=%g, factor=%g, score=%g), branching point=%g\n",
      nexterncands, SCIPvarGetName(bestcand), bestsol, bestobj,
      SCIPvarGetBranchFactor(bestcand), bestscore, brpoint);

   /* perform the branching */
   SCIP_CALL( SCIPbranchVarVal(scip, bestcand, brpoint, &downchild, &eqchild, &upchild) );

   if( downchild != NULL || eqchild != NULL || upchild != NULL )
   {
      *result = SCIP_BRANCHED;
   }
   else
   {
      /* if there are no children, then variable should have been fixed by SCIPbranchVarVal */
      assert(SCIPisEQ(scip, SCIPvarGetLbLocal(bestcand), SCIPvarGetUbLocal(bestcand)));
      *result = SCIP_REDUCEDDOM;
   }

   return SCIP_OKAY;
}
Example #4
0
/** selects a variable out of the given candidate array and performs the branching */
static
SCIP_RETCODE performBranching(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_VAR**            cands,              /**< candidate array */
   SCIP_Real*            candsols,           /**< array of candidate solution values, or NULL */
   int                   ncands,             /**< number of candidates */
   SCIP_Real             conflictweight,     /**< weight in score calculations for conflict score */
   SCIP_Real             inferenceweight,    /**< weight in score calculations for inference score */
   SCIP_Real             cutoffweight,       /**< weight in score calculations for cutoff score */
   SCIP_Real             reliablescore,      /**< score which is seen to be reliable for a branching decision */
   SCIP_Bool             useweightedsum,     /**< should a weighted sum of inference, conflict and cutoff weights be used? */
   SCIP_RESULT*          result              /**< buffer to store result (branched, reduced domain, ...) */
   )
{
   SCIP_VAR* bestaggrcand;
   SCIP_VAR* bestvaluecand;
   SCIP_Real bestval;
   SCIP_Real bestaggrscore;
   SCIP_Real bestvaluescore;
   SCIP_Real bestbranchpoint;
   SCIP_BRANCHDIR bestbranchdir;
   SCIP_NODE* downchild;
   SCIP_NODE* eqchild;
   SCIP_NODE* upchild;

   bestbranchpoint = SCIP_UNKNOWN;
   bestbranchdir = SCIP_BRANCHDIR_DOWNWARDS;
   bestvaluescore = 0.0;
   bestvaluecand = NULL;

   assert(ncands > 0);
   assert(result != NULL);

   *result = SCIP_DIDNOTFIND;

   /* check if the weighted sum between the average inferences and conflict score should be used */
   if( useweightedsum )
   {
      int c;

      bestaggrcand = cands[0];
      bestvaluecand = cands[0];
      assert(cands[0] != NULL);

      if( candsols == NULL )
      {
         bestval = SCIP_UNKNOWN;

         /* get domain value score for the first candidate */
         bestvaluescore = getValueScore(scip, cands[0], conflictweight, cutoffweight, reliablescore, &bestbranchpoint, &bestbranchdir);
         SCIPdebugMessage("current best value candidate <%s>[%g,%g] %s <%g> (value %g)\n",
            SCIPvarGetName(bestvaluecand), SCIPvarGetLbLocal(bestvaluecand), SCIPvarGetUbLocal(bestvaluecand),
            bestbranchdir == SCIP_BRANCHDIR_DOWNWARDS ? "<=" : ">=", bestbranchpoint, bestvaluescore);
      }
      else
         bestval = candsols[0];

      /* get aggregated score for the first candidate */
      bestaggrscore = getAggrScore(scip, cands[0], conflictweight, inferenceweight, cutoffweight, reliablescore);

      for( c = 1; c < ncands; ++c )
      {
         SCIP_VAR* cand;
         SCIP_Real val;
         SCIP_Real aggrscore;
         SCIP_Real branchpoint;
         SCIP_BRANCHDIR branchdir;

         cand = cands[c];
         assert(cand != NULL);

         if( candsols == NULL )
         {
            SCIP_Real valuescore;

            val = SCIP_UNKNOWN;

            /* get domain value score for the candidate */
            valuescore = getValueScore(scip, cand, conflictweight, cutoffweight, reliablescore, &branchpoint, &branchdir);

            /* evaluate the candidate against the currently best candidate w.r.t. domain value score */
            evaluateValueCand(cand, valuescore, branchpoint, branchdir, &bestvaluecand, &bestvaluescore, &bestbranchpoint, &bestbranchdir);

            SCIPdebugMessage("current best value candidate <%s>[%g,%g] %s <%g> (value %g)\n",
               SCIPvarGetName(bestvaluecand), SCIPvarGetLbLocal(bestvaluecand), SCIPvarGetUbLocal(bestvaluecand),
               bestbranchdir == SCIP_BRANCHDIR_DOWNWARDS ? "<=" : ">=", bestbranchpoint, bestvaluescore);
         }
         else
            val = candsols[c];

         /* get aggregated score for the candidate */
         aggrscore = getAggrScore(scip, cand, conflictweight, inferenceweight, cutoffweight, reliablescore);

         SCIPdebugMessage(" -> cand <%s>: prio=%d, solval=%g, score=%g\n", SCIPvarGetName(cand), SCIPvarGetBranchPriority(cand),
            val == SCIP_UNKNOWN ? SCIPgetVarSol(scip, cand) : val, aggrscore); /*lint !e777*/

         /* evaluate the candidate against the currently best candidate w.r.t. aggregated score */
         evaluateAggrCand(cand, aggrscore, val, &bestaggrcand, &bestaggrscore, &bestval);
      }
   }
   else
   {
      int c;

      bestaggrcand = cands[0];
      assert(cands[0] != NULL);

      if( candsols != NULL )
         bestval = candsols[0];
      else
         bestval = SCIP_UNKNOWN;

      bestaggrscore = SCIPgetVarAvgInferenceScore(scip, cands[0]);

      /* search for variable with best score w.r.t. average inferences per branching */
      for( c = 1; c < ncands; ++c )
      {
         SCIP_VAR* cand;
         SCIP_Real val;
         SCIP_Real aggrscore;

         cand = cands[c];
         assert(cand != NULL);

         if( candsols != NULL )
            val = candsols[c];
         else
            val = SCIP_UNKNOWN;

         aggrscore = SCIPgetVarAvgInferenceScore(scip, cand);

         /* in case the average inferences score is below the reliable score we set it to zero since it is seen to be
          * unreliable
          */
         if( aggrscore < reliablescore )
            aggrscore = 0.0;

         SCIPdebugMessage(" -> cand <%s>: prio=%d, solval=%g, score=%g\n", SCIPvarGetName(cand), SCIPvarGetBranchPriority(cand),
            val == SCIP_UNKNOWN ? SCIPgetVarSol(scip, cand) : val, aggrscore); /*lint !e777*/

         /* evaluate the candidate against the currently best candidate */
         evaluateAggrCand(cand, aggrscore, val, &bestaggrcand, &bestaggrscore, &bestval);
      }
   }

   assert(bestaggrcand != NULL);

   SCIPdebugMessage(" -> %d candidates, selected variable <%s>[%g,%g] (prio=%d, solval=%.12f, score=%g, conflict=%g cutoff=%g, inference=%g)\n",
      ncands, SCIPvarGetName(bestaggrcand), SCIPvarGetLbLocal (bestaggrcand), SCIPvarGetUbLocal(bestaggrcand), SCIPvarGetBranchPriority(bestaggrcand),
      bestval == SCIP_UNKNOWN ? SCIPgetVarSol(scip, bestaggrcand) : bestval, bestaggrscore, /*lint !e777*/
      SCIPgetVarConflictScore(scip, bestaggrcand),  SCIPgetVarAvgInferenceCutoffScore(scip, bestaggrcand, cutoffweight),
      SCIPgetVarAvgInferenceScore(scip, bestaggrcand));

   /* perform the branching */
   if( candsols != NULL )
   {
      SCIP_CALL( SCIPbranchVarVal(scip, bestaggrcand, SCIPgetBranchingPoint(scip, bestaggrcand, bestval), &downchild, &eqchild, &upchild) );
   }
   else if( bestbranchpoint == SCIP_UNKNOWN ) /*lint !e777*/
   {
      SCIP_CALL( SCIPbranchVar(scip, bestaggrcand, &downchild, &eqchild, &upchild) );
   }
   else
   {
      SCIP_Real estimate;
      SCIP_Real downprio;
      SCIP_Real upprio;
      SCIP_Real downub;
      SCIP_Real uplb;

      assert(bestvaluecand != NULL);

      downprio = 0.0;
      upprio = 0.0;

      if( bestbranchdir == SCIP_BRANCHDIR_DOWNWARDS )
      {
         downprio = 1.0;
         downub = bestbranchpoint;
         uplb = bestbranchpoint + 1.0;
      }
      else
      {
         upprio = 1.0;
         downub = bestbranchpoint - 1.0;
         uplb = bestbranchpoint;
      }

      /* calculate the child estimate */
      estimate = SCIPcalcChildEstimate(scip, bestvaluecand, downub);

      /* create down child */
      SCIP_CALL( SCIPcreateChild(scip, &downchild, downprio, estimate) );

      /* change upper bound in down child */
      SCIP_CALL( SCIPchgVarUbNode(scip, downchild, bestvaluecand, downub) );

      /* calculate the child estimate */
      estimate = SCIPcalcChildEstimate(scip, bestvaluecand, uplb);

      /* create up child */
      SCIP_CALL( SCIPcreateChild(scip, &upchild, upprio, estimate) );

      /* change lower bound in up child */
      SCIP_CALL( SCIPchgVarLbNode(scip, upchild, bestvaluecand, uplb) );

      SCIPdebugMessage("branch on variable <%s> and value <%g>\n", SCIPvarGetName(bestvaluecand), bestbranchpoint);

      eqchild = NULL;
   }

   if( downchild != NULL || eqchild != NULL || upchild != NULL )
   {
      *result = SCIP_BRANCHED;
   }
   else
   {
      /* if there are no children, then variable should have been fixed by SCIPbranchVar(Val) */
      assert(SCIPisEQ(scip, SCIPvarGetLbLocal(bestaggrcand), SCIPvarGetUbLocal(bestaggrcand)));
      *result = SCIP_REDUCEDDOM;
   }

   return SCIP_OKAY;
}