[Coin-discuss] Extracting the best solution in Cbc.
John J Forrest
jjforre at us.ibm.com
Wed Jan 18 20:28:11 EST 2006
Were you using pre-processing? If not it definitely should have worked.
If you are then there is now a cleaner way of doing pre-processing using
CbcStrategy - see Samples/repeat.cpp to give you a clue. If you that
fails it can you send me something to help debug - I did some tests and it
seemed Ok.
John Forrest
acw at ascent.com
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01/17/2006 05:07 PM
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[Coin-discuss] Extracting the best solution in Cbc.
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We are using a COIN/Cbc application that we created by making slight
modifications to the test example provided with Cbc.
What is the recommended way to extract the best feasible integer solution?
The documentation says to use CbcModel::bestSolution. We tried this, and
got bad (infeasible) results. The example application (in its
implementation of the SOLUTION command) uses CbcModel::getColSolution,
which is not documented. The documentation does mention
OsiSolverInterface::getColSolution, but this is deprecated (with somewhat
ambiguous language) in favor of CbcModel::bestSolution.
We decided to mimic the example, and tried the undocumented
CbcModel::getColSolution. This worked nicely with instances that ran to
completion, but when we added a time limit (with
CbcModel::setMaximumSeconds) the reported solution was again infeasible.
(CbcModel::branchAndBound did report finding several integer solutions in
the running time available.)
Thank you for your assistance. We are finding Cbc, overall, quite easy to
work with and adapt to our needs.
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