[Coin-discuss] CbcModel.isProvenInfeasible() returns true on time-outed problem

[John J Forrest]

Kish,

I am unable to reproduce the isProvenInfeasible problem.  BTW it is not a
good idea to set maximum time in solver - at best it will be meaningless
and at worst it may confuse the code.

As for isProvenPrimalFeasible() this would just be a cover for
bestSolution() so why not use that.  if (model.bestSolution()) then
solution exists.

John Forrest


                                                                           
             Kish Shen                                                     
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                                       CbcModel.isProvenInfeasible()       
             07/08/06 02:47 AM         returns true on      time-outed     
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Hi,

I have added timeout to my code by calling setMaximumSeconds() in the
OsiClpSolver, and in the CbcModel copied from the OsiClpSolver.

For the various problems that do timeout, when the CbcModel's
isProvenInfeasible() returns true when it is called after the (aborted)
branchAndBound.

If the branchAndBound did not finish, then neither optimality nor
infeasibility can be proven, so isProvenInfeasible() should return false.
In
fact, in some of the aborted MIP search, solutions were found, and so the
problem is proven to be feasible, rather than infeasible. [as I mentioned
in
a previous post, for my usage of the COIN libraries, it would be very
useful
to have a isProvenPrimalFeasible() call]

Cheers,

Kish
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