Merge branch '3940-fix-heur_alns-c-1379-void-tryadd2variablebuffer-scip-scip_var-double-scip_var-double-int-unsigned' into 'v92-bugfix'

Resolve "heur_alns.c:1379: void tryAdd2variableBuffer(SCIP *, SCIP_VAR *, double, SCIP_VAR **, double *, int *, unsigned int): Assertion `SCIPisFeasIntegral(scip, val) || ! SCIPvarIsIntegral(var)' failed."

See merge request integer/scip!3906

Author: DominikKamp

CHANGELOG

@@ -19,6 +19,8 @@ Fixed bugs
 - avoid overwriting set cutoff flag in tightenCoefs(), preprocessConstraintPairs(), and applyFixings() of cons_varbound.c to reject infeasible solutions
 - fix memory leak in exprinterpret_cppad.cpp w.r.t. user expressions
 - adjust bound before checking feasibility in SCIPvarAddVlb() and SCIPvarAddVub() to detect integrality cutoff
+- choose incumbent solution as reference in varFixingsRins() and varFixingsDins() of heur_alns.c to ensure integrality
+- consider variable type in selectInitialVariableRandomly() of heur_gins.c to count integral variables
 
 Build system
 ------------

check/CMakeLists.txt

@@ -517,6 +517,7 @@ set(pairs_Issue
     "instances/Issue/3932.cip\;+infinity\;reduced_tolerance"
     "instances/Issue/3934.cip\;-5007\;conflict_off_reduced_presolving_subrestart"
     "instances/Issue/3935.cip\;-24793.9840277416\;default"
+    "instances/Issue/3940.cip\;-2549.22\;unscaled_tolerance"
 )
 
 #

check/coverage/settings/unscaled_tolerance.set

@@ -0,0 +1,3 @@
+lp/scaling = 0
+numerics/sumepsilon = 1e-9
+numerics/feastol = 1e-9

check/instances/Issue/3940.cip

@@ -0,0 +1,22 @@
+STATISTICS
+  Problem name     : seed
+  Variables        : 5 (0 binary, 5 integer, 0 implicit integer, 0 continuous)
+  Constraints      : 0 initial, 8 maximal
+OBJECTIVE
+  Sense            : minimize
+VARIABLES
+  [integer] <x0>: obj=-78, original bounds=[-200,+inf]
+  [integer] <x1>: obj=-81.3, original bounds=[-200,+inf]
+  [integer] <x2>: obj=63, original bounds=[-200,+inf]
+  [integer] <x3>: obj=-84.66, original bounds=[0,200]
+  [integer] <x4>: obj=21, original bounds=[-200,+inf]
+CONSTRAINTS
+  [linear] <_C10>:  -24.52<x0>[I] -52.76<x1>[I] +94.84<x2>[I] -20.18<x3>[I] -79.99<x4>[I] >= -4291.3;
+  [linear] <_C11>:  -44<x2>[I] -47<x4>[I] <= 0;
+  [linear] <_C13>:  -49.18<x0>[I] +7.64<x1>[I] -36.45<x2>[I] +20.37<x3>[I] +32.91<x4>[I] <= 3645.24;
+  [linear] <_C14>:  +39<x2>[I] +45<x4>[I] >= 0;
+  [linear] <_C17>:  +81.01<x0>[I] +45.36<x1>[I] +91.01<x2>[I] -47.28<x3>[I] +34.98<x4>[I] <= -2042.31;
+  [linear] <_C4>:  -21<x1>[I] >= 0;
+  [linear] <_C5>:  +59.51<x3>[I] +92.41<x4>[I] >= 0;
+  [linear] <_C6>:  -22.28<x0>[I] -1.96<x1>[I] +84.7<x2>[I] -83.65<x3>[I] +88.9<x4>[I] >= 185.1;
+END

src/scip/heur_alns.c

@@ -1338,7 +1338,7 @@ SCIP_Real getVariablePscostScore(
    SCIP_Bool             uselocallpsol       /**< should local LP solution be used? */
    )
 {
-   SCIP_Real lpsolval;
+   SCIP_Real soldiff;
 
    assert(scip != NULL);
    assert(var != NULL);
@@ -1347,13 +1347,13 @@ SCIP_Real getVariablePscostScore(
    if( SCIPvarGetStatus(var) != SCIP_VARSTATUS_COLUMN )
       return 0.0;
 
-   lpsolval = uselocallpsol ? SCIPvarGetLPSol(var) : SCIPvarGetRootSol(var);
+   soldiff = refsolval - (uselocallpsol ? SCIPvarGetLPSol(var) : SCIPvarGetRootSol(var));
 
    /* the score is 0.0 if the values are equal */
-   if( SCIPisEQ(scip, lpsolval, refsolval) )
+   if( SCIPisFeasZero(scip, soldiff) )
       return 0.0;
    else
-      return SCIPgetVarPseudocostVal(scip, var, refsolval - lpsolval);
+      return SCIPgetVarPseudocostVal(scip, var, soldiff);
 }
 
 /** add variable and solution value to buffer data structure for variable fixings. The method checks if
@@ -1370,12 +1370,8 @@ void tryAdd2variableBuffer(
    SCIP_Bool             integer             /**< is this an integer variable? */
    )
 {
-   /* todo: this assert can fail when there was a dual reduction that changed a variable to
-    * an integral type after the reference solution was found and the variable has a fractional
-    * value in this solution, e.g., for boxQP instances (spar*)
-    * implicit integer variables could also be an issue, as they can take fractional values in feasible solutions
-    */
-   assert(SCIPisFeasIntegral(scip, val) || ! SCIPvarIsIntegral(var));
+   assert(integer == (SCIPvarGetType(var) == SCIP_VARTYPE_BINARY || SCIPvarGetType(var) == SCIP_VARTYPE_INTEGER));
+   assert(!integer || SCIPisFeasIntegral(scip, val));
    assert(*nfixings < SCIPgetNVars(scip));
 
    /* round the value to its nearest integer */
@@ -2774,9 +2770,13 @@ DECL_VARFIXINGS(varFixingsRens)
    /* loop over binary and integer variables; determine those that should be fixed in the sub-SCIP */
    for( nfracs = 0, i = 0; i < nbinvars + nintvars; ++i )
    {
-      SCIP_VAR* var = vars[i];
-      SCIP_Real lpsolval = SCIPvarGetLPSol(var);
-      assert((i < nbinvars && SCIPvarIsBinary(var)) || (i >= nbinvars && SCIPvarIsIntegral(var)));
+      SCIP_VAR* var;
+      SCIP_Real lpsolval;
+
+      var = vars[i];
+      assert(SCIPvarGetType(var) == SCIP_VARTYPE_BINARY || SCIPvarGetType(var) == SCIP_VARTYPE_INTEGER);
+      assert((i < nbinvars) == (SCIPvarGetType(var) == SCIP_VARTYPE_BINARY));
+      lpsolval = SCIPvarGetLPSol(var);
 
       /* fix all binary and integer variables with integer LP solution value */
       if( SCIPisFeasIntegral(scip, lpsolval) )
@@ -2897,19 +2897,19 @@ SCIP_RETCODE fixMatchingSolutionValues(
    /* loop over integer and binary variables and check if their solution values match in all solutions */
    for( v = 0; v < nvars; ++v )
    {
-      SCIP_Real solval;
       SCIP_VAR* var;
+      SCIP_Real solval;
       int s;
 
       var = vars[v];
-      assert((v < SCIPgetNBinVars(scip) && SCIPvarIsBinary(var)) || (v >= SCIPgetNBinVars(scip) && SCIPvarIsIntegral(var)));
+      assert(SCIPvarGetType(var) == SCIP_VARTYPE_BINARY || SCIPvarGetType(var) == SCIP_VARTYPE_INTEGER);
+      assert((v < SCIPgetNBinVars(scip)) == (SCIPvarGetType(var) == SCIP_VARTYPE_BINARY));
       solval = SCIPgetSolVal(scip, firstsol, var);
 
       /* determine if solution values match in all given solutions */
       for( s = 1; s < nsols; ++s )
       {
-         SCIP_Real solval2 = SCIPgetSolVal(scip, sols[s], var);
-         if( ! SCIPisEQ(scip, solval, solval2) )
+         if( !SCIPisFeasZero(scip, solval - SCIPgetSolVal(scip, sols[s], var)) )
             break;
       }
 
@@ -2961,8 +2961,9 @@ DECL_VARFIXINGS(varFixingsRins)
    if( nbinvars + nintvars == 0 )
       return SCIP_OKAY;
 
-   sols[0] = NULL;
-   sols[1] = incumbent;
+   /* incumbent is reference */
+   sols[0] = incumbent;
+   sols[1] = NULL;
 
    SCIP_CALL( fixMatchingSolutionValues(scip, sols, 2, vars, nbinvars + nintvars, varbuf, valbuf, nfixings) );
 
@@ -3518,11 +3519,11 @@ DECL_VARFIXINGS(varFixingsDins)
    nsols = nmipsols + 2;
 
    SCIP_CALL( SCIPallocBufferArray(scip, &sols, nsols) );
-   sols[0] = NULL; /* node LP solution */
-   sols[1] = rootlpsol;
 
-   /* copy the remaining MIP solutions after the LP solutions */
-   BMScopyMemoryArray(&sols[2], SCIPgetSols(scip), nmipsols); /*lint !e866*/
+   /* incumbent is reference */
+   BMScopyMemoryArray(sols, SCIPgetSols(scip), nmipsols); /*lint !e866*/
+   sols[nmipsols] = NULL;
+   sols[nmipsols + 1] = rootlpsol;
 
    /* 1. Binary variables are fixed if their values agree in all the solutions */
    if( nbinvars > 0 )

src/scip/heur_gins.c

@@ -1610,7 +1610,7 @@ SCIP_RETCODE selectInitialVariableRandomly(
          break;
       }
 
-      assert(SCIPvarIsIntegral(choosevar));
+      assert(SCIPvarGetType(choosevar) == SCIP_VARTYPE_BINARY || SCIPvarGetType(choosevar) == SCIP_VARTYPE_INTEGER);
 
       /* get neighborhood storage */
       SCIP_CALL( SCIPallocBufferArray(scip, &neighborhood, nvars) );
@@ -1643,7 +1643,7 @@ SCIP_RETCODE selectInitialVariableRandomly(
             neighborhood[neighborhoodsize++] = currvar;
 
             /* increase discrete variables counter */
-            if( SCIPvarIsIntegral(currvar) )
+            if( SCIPvarGetType(currvar) <= SCIP_VARTYPE_INTEGER )
                ++ndiscvarsneighborhood;
          }
       }