Created stem for lnsCarrara

Author: jajhall

highs/lp_data/HighsOptions.h

@@ -445,6 +445,7 @@ struct HighsOptionsStruct {
   bool mip_heuristic_run_root_reduced_cost;
   bool mip_heuristic_run_zi_round;
   bool mip_heuristic_run_shifting;
+  bool mip_heuristic_run_lns_carrara;
   double mip_min_logging_interval;
 
 #ifdef HIGHS_DEBUGSOL
@@ -596,6 +597,7 @@ struct HighsOptionsStruct {
         mip_heuristic_run_root_reduced_cost(false),
         mip_heuristic_run_zi_round(false),
         mip_heuristic_run_shifting(false),
+        mip_heuristic_run_lns_carrara(false),
         mip_min_logging_interval(0.0),
 #ifdef HIGHS_DEBUGSOL
         mip_debug_solution_file(""),
@@ -1168,6 +1170,12 @@ class HighsOptions : public HighsOptionsStruct {
                                        &mip_heuristic_run_shifting, false);
     records.push_back(record_bool);
 
+    record_bool = new OptionRecordBool(
+        "mip_heuristic_run_lns_carrara",
+        "Use the large neighbourhood search (carrara) heuristic", advanced,
+        &mip_heuristic_run_lns_carrara, false);
+    records.push_back(record_bool);
+
     record_double = new OptionRecordDouble(
         "mip_rel_gap",
         "Tolerance on relative gap, |ub-lb|/|ub|, to determine whether "

highs/mip/HighsMipSolverData.cpp

@@ -1768,6 +1768,10 @@ HighsLpRelaxation::Status HighsMipSolverData::evaluateRootLp() {
           mipsolver.options_mip_->mip_heuristic_run_zi_round)
         heuristics.ziRound(lp.getLpSolver().getSolution().col_value);
 
+      if (status == HighsLpRelaxation::Status::kOptimal &&
+          mipsolver.options_mip_->mip_heuristic_run_lns_carrara)
+        heuristics.lnsCarrara(lp.getLpSolver().getSolution().col_value);
+
     } else
       status = lp.getStatus();
 

highs/mip/HighsPrimalHeuristics.cpp

@@ -1634,6 +1634,9 @@ void HighsPrimalHeuristics::clique() {
 }
 #endif
 
+void HighsPrimalHeuristics::lnsCarrara(
+    const std::vector<double>& relaxationsol) {}
+
 void HighsPrimalHeuristics::flushStatistics() {
   mipsolver.mipdata_->total_repair_lp += total_repair_lp;
   mipsolver.mipdata_->total_repair_lp_feasible += total_repair_lp_feasible;

highs/mip/HighsPrimalHeuristics.h

@@ -69,6 +69,8 @@ class HighsPrimalHeuristics {
   void shifting(const std::vector<double>& relaxationsol);
 
   void ziRound(const std::vector<double>& relaxationsol);
+
+  void lnsCarrara(const std::vector<double>& relaxationsol);
 };
 
 #endif

highs/mip/MipTimer.h

@@ -22,6 +22,7 @@ enum iClockMip {
   kMipClockRunPresolve,
   kMipClockRunSetup,
   kMipClockFeasibilityJump,
+  kMipClockLnsCarrara,
   kMipClockTrivialHeuristics,
   kMipClockEvaluateRootNode,
   kMipClockPerformAging0,
@@ -138,6 +139,7 @@ class MipTimer {
     clock[kMipClockRunSetup] = timer_pointer->clock_def("Run setup");
     clock[kMipClockFeasibilityJump] =
         timer_pointer->clock_def("Feasibility jump");
+    clock[kMipClockLnsCarrara] = timer_pointer->clock_def("LNS (carrara)");
     clock[kMipClockTrivialHeuristics] =
         timer_pointer->clock_def("Trivial heuristics");
     clock[kMipClockEvaluateRootNode] =
@@ -324,6 +326,7 @@ class MipTimer {
                                                kMipClockRunPresolve,
                                                kMipClockRunSetup,
                                                kMipClockFeasibilityJump,
+                                               kMipClockLnsCarrara,
                                                kMipClockTrivialHeuristics,
                                                kMipClockEvaluateRootNode,
                                                kMipClockPerformAging0,