Merge branch '3942-fix-invalid-solution-for-infeasible-instance-violation-right-hand-side-is-violated-by-46' into 'v92-bugfix'

Resolve "Invalid solution for infeasible instance - violation: right hand side is violated by 46.5100000000002"

See merge request integer/scip!3910

Author: DominikKamp

CHANGELOG

@@ -21,6 +21,7 @@ Fixed bugs
 - 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
+- correct fractionality sign when standardizing bounds in simplifyInequalities() of cons_linear.c
 
 Build system
 ------------

check/CMakeLists.txt

@@ -518,6 +518,7 @@ set(pairs_Issue
     "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"
+    "instances/Issue/3942.cip\;0\;default"
 )
 
 #

check/instances/Issue/3942.cip

@@ -0,0 +1,16 @@
+STATISTICS
+  Problem name     : instance
+  Variables        : 3 (0 binary, 3 integer, 0 implicit integer, 0 continuous)
+  Constraints      : 0 initial, 4 maximal
+OBJECTIVE
+  Sense            : minimize
+VARIABLES
+  [integer] <x0>: obj=0, original bounds=[-200,200]
+  [integer] <x1>: obj=0, original bounds=[-200,200]
+  [integer] <x2>: obj=0, original bounds=[-200,200]
+CONSTRAINTS
+  [linear] <_C1>:  +73<x0>[I] -36<x1>[I] +80<x2>[I] <= 4120;
+  [linear] <_C2>:  +4.5<x0>[I] -82<x1>[I] -98<x2>[I] <= 2483.99;
+  [linear] <_C4>:  +54<x0>[I] +0.5<x1>[I] +30<x2>[I] <= 468;
+  [linear] <_C5>:  -18<x0>[I] +60<x1>[I] -48<x2>[I] <= -12910;
+END

src/scip/cons_linear.c

@@ -12206,7 +12206,7 @@ SCIP_RETCODE simplifyInequalities(
                   /* swap bounds for 'standard' form */
                   if( !SCIPisFeasZero(scip, lb) )
                   {
-                     ub = lb;
+                     ub = -lb;
                      val *= -1;
                   }
 
@@ -12299,7 +12299,7 @@ SCIP_RETCODE simplifyInequalities(
                   /* swap bounds for 'standard' form */
                   if( !SCIPisFeasZero(scip, lb) )
                   {
-                     ub = lb;
+                     ub = -lb;
                      val *= -1;
                   }