From 3b049ec384abbfc43f1e5d7c62dd0c6735a5068a Mon Sep 17 00:00:00 2001
From: John Forrest <jjhforrest@gmail.com>
Date: Mon, 4 Sep 2023 10:09:13 +0100
Subject: [PATCH] Trying to improve lazy constraints

---
 src/CbcCutGenerator.cpp | 30 +++++++++++++-----------------
 src/CbcModel.cpp        | 13 +++++++++++--
 src/CbcSolver.cpp       |  9 +++++++++
 3 files changed, 33 insertions(+), 19 deletions(-)

diff --git a/src/CbcCutGenerator.cpp b/src/CbcCutGenerator.cpp
index e6e09c121..fdbbbcd75 100644
--- a/src/CbcCutGenerator.cpp
+++ b/src/CbcCutGenerator.cpp
@@ -764,7 +764,7 @@ bool CbcCutGenerator::generateCuts(OsiCuts &cs, int fullScan, OsiSolverInterface
       const double *colLower = solver->getColLower();
       double smallValue1; // = 1.0e-4;
       double smallValue2; // = 1.0e-5;
-      double largeRatio = 1.0e8;
+      double largeRatio = 1.0e9;
       if (!depth) {
 	smallValue1 = 1.0e-5;
 	smallValue2 = 1.0e-5;
@@ -908,6 +908,7 @@ bool CbcCutGenerator::generateCuts(OsiCuts &cs, int fullScan, OsiSolverInterface
 	  double smallest=1.0e30;
 	  bool bad=false;
 	  double sum = 0.0;
+	  double origRhs = rhs;
 	  int number = 0;
 	  for (int i=0;i<n;i++) {
 	    double value=elements[i];
@@ -966,25 +967,20 @@ bool CbcCutGenerator::generateCuts(OsiCuts &cs, int fullScan, OsiSolverInterface
 	      }
 	    } else {
 	      int iColumn = indices[i];
-	      if (colUpper[iColumn]!=colLower[iColumn]) {
-		largest=CoinMax(largest,value);
-		smallest=CoinMin(smallest,value);
-		indices[number]=indices[i];
-		elements[number++]=elements[i];
-	      } else {
-		// fixed so subtract out
-		rhs -= elements[i]*colLower[iColumn];
-	      }
+	      largest=CoinMax(largest,value);
+	      smallest=CoinMin(smallest,value);
+	      indices[number]=indices[i];
+	      elements[number++]=elements[i];
 	    }
 	  }
-	  //if (number>80)
-	  //bad = true;
-	  if (largest<largeRatio*smallest&&!bad) {
-	    if (number<n)
-	      rpv.truncate(number);
-	  } else if (!bad) {
+	  if (rhs!=origRhs) {
+	    if (upper)
+	      thisCut->setUb(rhs);
+	    else
+	      thisCut->setLb(rhs);
 	  }
-	  if (bad) {
+	  if (bad || largest > largeRatio*smallest) {
+	    // safer to throw away
 	    cs.eraseRowCut(k);
 	  }
 	}
diff --git a/src/CbcModel.cpp b/src/CbcModel.cpp
index c70342a5b..36287702b 100644
--- a/src/CbcModel.cpp
+++ b/src/CbcModel.cpp
@@ -16397,8 +16397,7 @@ int CbcModel::chooseBranch(CbcNode *&newNode, int numberPassesLeft,
       }
     }
     if (solverCharacteristics_ &&
-        solverCharacteristics_
-            ->solutionAddsCuts() && // we are in some OA based bab
+        solverCharacteristics_->solverType()>2 && // we are in some OA based bab
         feasible &&
         (newNode->numberUnsatisfied() ==
          0) // solution has become integer feasible during strong branching
@@ -16422,7 +16421,12 @@ int CbcModel::chooseBranch(CbcNode *&newNode, int numberPassesLeft,
       resolve(solver_);
       double objval = solver_->getObjValue();
       lastHeuristic_ = NULL;
+      // switch off odd stuff if no cuts were found
+      int solverType = solverCharacteristics_->solverType();
+      if (feasCuts.sizeCuts()==0 && solverCharacteristics_->solverType()>2) 
+	solverCharacteristics_->setSolverType(0);
       setBestSolution(CBC_SOLUTION, objval, solver_->getColSolution());
+      solverCharacteristics_->setSolverType(solverType);
       int easy = 2;
       if (!solverCharacteristics_
                ->mipFeasible()) // did we prove that the node could be pruned?
@@ -18503,6 +18507,11 @@ int CbcModel::doOneNode(CbcModel *baseModel, CbcNode *&node,
               // need dummy branch
               newNode->setBranchingObject(new CbcDummyBranchingObject(this));
               newNode->nodeInfo()->initializeInfo(1);
+	      // add in cuts
+	      for (int i=0;i<numberRowCutsAfter;i++) {
+		theseCuts.rowCut(i).setEffectiveness(COIN_DBL_MAX);
+		globalCuts_.addCutIfNotDuplicate(theseCuts.rowCut(i));
+	      }
             }
           }
         }
diff --git a/src/CbcSolver.cpp b/src/CbcSolver.cpp
index dd5ebee11..5fa5f383f 100644
--- a/src/CbcSolver.cpp
+++ b/src/CbcSolver.cpp
@@ -1090,6 +1090,15 @@ int CbcMain1(std::deque<std::string> inputQueue, CbcModel &model,
   std::ostringstream buffer;
   std::string field, message, fileName;
   FILE *fp;
+#ifdef DEBUG_CBC_PYTHON
+  // Probably being stupid but finding it difficult to debug from python
+  static int startedPython=0;
+  if (!startedPython) {
+    printf("debug python:");
+    getchar();
+    startedPython=1;
+  }
+#endif
 
   double totalTime = parameters.getTotalTime();
   bool useSignalHandler = parameters.useSignalHandler();