From 51159cfc51caeb9bf75d5b3adf6bdeb0ef3c277f Mon Sep 17 00:00:00 2001
From: John Forrest <jjhforrest@gmail.com>
Date: Tue, 29 Aug 2023 09:24:42 +0100
Subject: [PATCH] modifications for lazy constraints

---
 src/CbcModel.cpp  | 41 +++++++++++++++++++++++++----------------
 src/CbcSolver.cpp |  8 +++++---
 2 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/src/CbcModel.cpp b/src/CbcModel.cpp
index 58bf82350..4fad21975 100644
--- a/src/CbcModel.cpp
+++ b/src/CbcModel.cpp
@@ -1253,10 +1253,18 @@ void CbcModel::analyzeObjective()
       value *= scaleFactor;
       // trueIncrement=CoinMax(cutoff,value);;
       if (value * 0.999 > cutoff) {
-        messageHandler()->message(CBC_INTEGERINCREMENT, messages())
+	if ((moreSpecialOptions2_ & 65536) == 0) {
+	  messageHandler()->message(CBC_INTEGERINCREMENT, messages())
             << value << CoinMessageEol;
-        setDblParam(CbcModel::CbcCutoffIncrement,
-                    CoinMax(value * 0.999, value - 1.0e-4));
+	  setDblParam(CbcModel::CbcCutoffIncrement,
+		      CoinMax(value * 0.999, value - 1.0e-4));
+	} else {
+	  // lazy constraints - can't be certain
+	  char temp[100];
+	  sprintf(temp,"May be able to increase cutoff increment to %g - but we have lazy constraints",CoinMax(value*0.999,value-1.0e-4));
+	  messageHandler()->message(CBC_GENERAL, messages())
+            << temp << CoinMessageEol;
+	}
       }
     }
   }
@@ -2375,9 +2383,10 @@ void CbcModel::branchAndBound(int doStatistics)
 #endif
   bool feasible;
   numberSolves_ = 0;
-  {
-    // check
+  if (!parentModel_) {
     int numberOdd = 0;
+    moreSpecialOptions2_ &= ~65536; // say no lazy constraints
+    // check
     int numberSOS = 0;
     for (int i = 0; i < numberObjects_; i++) {
       CbcSimpleInteger *obj = dynamic_cast<CbcSimpleInteger *>(object_[i]);
@@ -2395,18 +2404,18 @@ void CbcModel::branchAndBound(int doStatistics)
 #endif
         specialOptions_ &= ~(512 | 32768);
     }
-    moreSpecialOptions2_ &= ~65536; // say no lazy constraints
-    if (!numberOdd && !parentModel_) {
-      // see if lazy constraints
-      bool needCuts = false;
-      for (int i = 0; i < numberCutGenerators_; i++) {
-        bool generate = generator_[i]->atSolution();
-        if (generate) {
-          needCuts = true;
-        }
+    // see if lazy constraints
+    bool needCuts = false;
+    for (int i = 0; i < numberCutGenerators_; i++) {
+      bool generate = generator_[i]->atSolution();
+      if (generate) {
+	needCuts = true;
       }
-      if (needCuts)
-        moreSpecialOptions2_ |= 65536; // lazy constraints
+    }
+    if (needCuts) {
+      moreSpecialOptions2_ |= 65536; // lazy constraints
+      // switch off nauty
+      moreSpecialOptions2_ &= ~(128|256);
     }
   }
   // If NLP then we assume already solved outside branchAndbound
diff --git a/src/CbcSolver.cpp b/src/CbcSolver.cpp
index f643922a2..dd5ebee11 100644
--- a/src/CbcSolver.cpp
+++ b/src/CbcSolver.cpp
@@ -2310,7 +2310,7 @@ int CbcMain1(std::deque<std::string> inputQueue, CbcModel &model,
                     buffer.str("");
                     buffer << "switching on global root cuts for gomory and "
                            << "knapsack" << std::endl;
-                    buffer << "using OSL factorization" << std::endl;
+                    //buffer << "using OSL factorization" << std::endl;
                     buffer << "extra options - -rens on -extra4 " << extra4
                            << " -passc 1000!" << std::endl;
                     printGeneralMessage(model_, buffer.str());
@@ -2321,7 +2321,7 @@ int CbcMain1(std::deque<std::string> inputQueue, CbcModel &model,
                     parameters[CbcParam::KNAPSACKCUTS]->setVal("onGlobal");
                     knapsackMode = CbcParameters::CGOnGlobal;
                     clpParameters[ClpParam::FACTORIZATION]->setVal("osl");
-                    lpSolver->factorization()->forceOtherFactorization(3);
+                    //lpSolver->factorization()->forceOtherFactorization(3);
                     parameters[CbcParam::MAXHOTITS]->setVal(100);
                     parameters[CbcParam::CUTPASS]->setVal(1000);
                     cutPass = 1000;
@@ -6339,9 +6339,11 @@ int CbcMain1(std::deque<std::string> inputQueue, CbcModel &model,
               double increment = babModel_->getCutoffIncrement();
               ;
               int *changed = NULL;
-              if (!miplib && increment == normalIncrement)
+#ifdef UNSAFE_FOR_LAZY_CUTS
+              if (!miplib && increment == normalIncrement) 
                 changed = analyze(osiclp, numberChanged, increment, false,
                                   generalMessageHandler, parameters.noPrinting());
+#endif
 #elif CBC_OTHER_SOLVER == 1
               double increment = babModel_->getCutoffIncrement();
               ;