Corrected TEST_CASE("IP-infeasible-unbounded" now that kInfeasible an…

…d kUnbounded are distinguished when presolve is off
ERGO-Code · Nov 5, 2024 · 5e6ec3e · 5e6ec3e
1 parent 919774e
commit 5e6ec3e
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Showing 4 changed files with 30 additions and 7 deletions.
diff --git a/check/TestMipSolver.cpp b/check/TestMipSolver.cpp
@@ -677,8 +677,17 @@ TEST_CASE("IP-infeasible-unbounded", "[highs_test_mip_solver]") {
       // Solve
       highs.passModel(lp);
       highs.run();
-      REQUIRE(highs.getModelStatus() ==
-              HighsModelStatus::kUnboundedOrInfeasible);
+      HighsModelStatus required_model_status;
+      if (k == 0) {
+        if (l == 0) {
+          required_model_status = HighsModelStatus::kInfeasible;
+        } else {
+          required_model_status = HighsModelStatus::kUnbounded;
+        }
+      } else {
+        required_model_status = HighsModelStatus::kUnboundedOrInfeasible;
+      }
+      REQUIRE(highs.getModelStatus() == required_model_status);
     }
     highs.setOptionValue("presolve", kHighsOnString);
   }

diff --git a/src/mip/HighsMipSolver.cpp b/src/mip/HighsMipSolver.cpp
@@ -177,7 +177,14 @@ void HighsMipSolver::run() {
     }
     // Apply the trivial heuristics
     analysis_.mipTimerStart(kMipClockTrivialHeuristics);
-    mipdata_->trivialHeuristics();
+    HighsModelStatus model_status = mipdata_->trivialHeuristics();
+    if (modelstatus_ == HighsModelStatus::kNotset &&
+        model_status == HighsModelStatus::kInfeasible) {
+      // trivialHeuristics can spot trivial infeasibility, so act on it
+      modelstatus_ = model_status;
+      cleanupSolve();
+      return;
+    }
     analysis_.mipTimerStop(kMipClockTrivialHeuristics);
     if (analysis_.analyse_mip_time & !submip)
       highsLogUser(options_mip_->log_options, HighsLogType::kInfo,

diff --git a/src/mip/HighsMipSolverData.cpp b/src/mip/HighsMipSolverData.cpp
@@ -166,7 +166,7 @@ bool HighsMipSolverData::solutionRowFeasible(
   return true;
 }
 
-void HighsMipSolverData::trivialHeuristics() {
+HighsModelStatus HighsMipSolverData::trivialHeuristics() {
   //  printf("\nHighsMipSolverData::trivialHeuristics() Number of continuous
   //  columns is %d\n",
   //	 int(continuous_cols.size()));
@@ -176,8 +176,8 @@ void HighsMipSolverData::trivialHeuristics() {
       kSolutionSourceTrivialZ, kSolutionSourceTrivialL, kSolutionSourceTrivialU,
       kSolutionSourceTrivialP};
 
-  const std::vector<double>& col_lower = mipsolver.model_->col_lower_;
-  const std::vector<double>& col_upper = mipsolver.model_->col_upper_;
+  std::vector<double> col_lower = mipsolver.model_->col_lower_;
+  std::vector<double> col_upper = mipsolver.model_->col_upper_;
   const std::vector<double>& row_lower = mipsolver.model_->row_lower_;
   const std::vector<double>& row_upper = mipsolver.model_->row_upper_;
   const HighsSparseMatrix& matrix = mipsolver.model_->a_matrix_;
@@ -189,6 +189,12 @@ void HighsMipSolverData::trivialHeuristics() {
   bool all_integer_upper_finite = true;
   for (HighsInt integer_col = 0; integer_col < numintegercols; integer_col++) {
     HighsInt iCol = integer_cols[integer_col];
+    // Round bounds in to nearest integer
+    col_lower[iCol] = std::ceil(col_lower[iCol]);
+    col_upper[iCol] = std::floor(col_upper[iCol]);
+    // If bounds are inconsistent then MIP is infeasible
+    if (col_lower[iCol] > col_upper[iCol]) return HighsModelStatus::kInfeasible;
+
     if (col_lower[iCol] > 0) all_integer_lower_non_positive = false;
     if (col_lower[iCol]) all_integer_lower_zero = false;
     if (col_lower[iCol] <= -kHighsInf) all_integer_lower_finite = false;
@@ -288,6 +294,7 @@ void HighsMipSolverData::trivialHeuristics() {
       }
     }
   }
+  return HighsModelStatus::kNotset;
 }
 
 void HighsMipSolverData::startAnalyticCenterComputation(

diff --git a/src/mip/HighsMipSolverData.h b/src/mip/HighsMipSolverData.h
@@ -204,7 +204,7 @@ struct HighsMipSolverData {
   }
 
   bool solutionRowFeasible(const std::vector<double>& solution) const;
-  void trivialHeuristics();
+  HighsModelStatus trivialHeuristics();
 
   void startAnalyticCenterComputation(
       const highs::parallel::TaskGroup& taskGroup);