[Cbc] issue with cbcstrategy on small MILP

[John J Forrest]

Matt,

I fixed several bugs in preprocessing in the last few weeks but only in 
trunk.  trunk seems Okay, but the first two things I tried in stable/2.2 
did not fix problem.  It may take me some time to track down if you need 
it fixed in stable.

John





[Cbc] issue with cbcstrategy on small MILP

Matthew Galati 
to:
cbc at list.coin-or.org
11/03/2008 01:45 PM


Sent by:
cbc-bounces at list.coin-or.org







If I solve without the CbcStrategy, it solves the problem. If I use the 
default CbcStrategy, it claims infeasible.

.lp file is attached

Thanks,
Matt


Without Strategy:
Cbc0032I Strong branching done 34 times (49 iterations), fathomed 3 nodes 
and fixed 3 variables
Cbc0035I Maximum depth 3, 36 variables fixed on reduced cost
Clp0000I Optimal - objective value -137.844
Clp0000I Optimal - objective value -137.844


With Strategy:
Clp0000I Optimal - objective value -138.653
Clp0000I Optimal - objective value -138.653
Cbc0001I Search completed - best objective 1e+50, took 392 iterations and 
0 nodes (0.22 seconds)
Cbc0035I Maximum depth 0, 0 variables fixed on reduced cost
Clp0006I 0  Obj -138.653 Primal inf 25.5703 (9) Dual inf 2.77501e+11 (3)
Clp0006I 4  Obj -132.969 Primal inf 5 (5)
Clp0001I Primal infeasible - objective value -132.969

#include "CbcModel.hpp"
#include "CbcStrategy.hpp"
#include "OsiClpSolverInterface.hpp"

int main(int argc, char ** argv){
   OsiClpSolverInterface si;
   si.readLp("subProbInitCbc.lp");

   CbcModel cbc(si);

   CbcStrategyDefault cbcStrategyDefault;
   cbc.setStrategy(cbcStrategyDefault);

   cbc.branchAndBound();
   return 0;
}





[attachment "subProbInitCbc.lp" deleted by John J Forrest/Watson/IBM] 
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