[Cbc] defining a custom cut generator

[Tobias Stengel]

Hello,

I was able to reduce it tot he following:

#include <CglCutGenerator.hpp>
#include <OsiSolverInterface.hpp>
#include <OsiClpSolverInterface.hpp>
#include <iostream>
#include <CbcModel.hpp>

class CustomCutGenerator : public CglCutGenerator
{
public:
                CustomCutGenerator() {}

                CustomCutGenerator(const CustomCutGenerator &)
                {
                }

                virtual ~CustomCutGenerator()
                {
                }

                CustomCutGenerator &
                               operator=(
                               const CustomCutGenerator& rhs) {

                               return *this;
                }

                std::string generateCpp(FILE* file) override
                {
                               return "foo";
                }

                void generateCuts(const OsiSolverInterface &si, OsiCuts &cs, const CglTreeInfo info = CglTreeInfo()) override
                {
                }

                CglCutGenerator* clone() const override
                {
                               return new CustomCutGenerator(*this);
                }
};

int main(int argc,  char* argv[])
{
                std::cout << "foo" << std::endl;

                OsiClpSolverInterface solver1;
                int numMpsReadErrors = solver1.readMps("noswot","mps");
                if (numMpsReadErrors != 0)
                {
                               std::cout << "read model failed" << std::endl;
                               return 1;
                }

                CbcModel* model = new CbcModel(solver1);
                CustomCutGenerator cutGenerator;
                // this is the critical line. comment out and it works
                model->addCutGenerator(&cutGenerator);

                OsiClpSolverInterface* solver = dynamic_cast<OsiClpSolverInterface*>(model->solver());

                CbcMain0(*model);

                const char * argv2[] = { "driver4", "-solve", "-quit" };

                CbcMain1(3, argv2, *model);

                return 0;
}

My next step: try to build it under linux and see what valgrind says - hopefully tomorrow.

Tobias

Von: Cbc [mailto:cbc-bounces at coin-or.org] Im Auftrag von John Forrest
Gesendet: Dienstag, 10. Mai 2016 14:57
An: cbc at list.coin-or.org
Betreff: Re: [Cbc] defining a custom cut generator

Tobias,

Odd.  By default the variable  switchOffIfLessThan_ in a CbcCutGenerator is zero.  This means that you would not get to 9401 as it would fail test -

 if (generator_[i]->switchOffIfLessThan() < 0) {

at line 9398.

What value is switchOffIfLessThan_ when assert happens?  You do not reference CbcCutGenerator so how is the generator being added to CbcModel?

John Forrest

On 10/05/16 13:02, Tobias Stengel wrote:
Hi all,

I am trying to define my on cut generator. My test problem is noswot problem from miplib 3. When I add the following generator (reduced from my generator) to my model, the assert "assert (iSwitch >= 0 && iSwitch < 2);" in CbcModel.cpp, line 9401 fails. If compiled in release mode (turning asserts off), the correct solution is found.

             CustomCutGenerator::CustomCutGenerator() : CglCutGenerator() { }

             CustomCutGenerator::CustomCutGenerator(const CustomCutGenerator & other) {}

             CustomCutGenerator::~CustomCutGenerator()
             {}

             std::string CustomCutGenerator::generateCpp(FILE* file)
             {
                    return "customCutGenerator";
             }

             void CustomCutGenerator::generateCuts(const OsiSolverInterface &si, OsiCuts &cs, const CglTreeInfo info)
             {}

             CglCutGenerator* CustomCutGenerator::clone() const
             {
                    return new CustomCutGenerator();
             }

             CustomCutGenerator & CustomCutGenerator::operator=(const CustomCutGenerator& rhs) {
                    return *this;
             }

CustomCutGenerator implements CglCutGenerator. Any help why this happens and/or how to fix it would be welcomed. Especially since the user guide chapter on cuts is empty. Feel free to ask for more information.

I am using Cbc 2.9.8 and Microsoft visual C++ 2013.


Thanks
Tobias




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