[Cbc] Postprocessing in cbc

[Alexander Timmermeister]

Hi all,

I am using cbc in my application to solve a network flow problem. Since the problems can get quite big and are always MIPs, I made use of model->setAllowableFractionGap(double gap) and model->setHeuristicFractionGap(double gap). I am pretty sure I know what the first one does, but the documentation did not really help me understand what the second one does. Can anyone tell me?

Furthermore, after setting the gap to 0.1, the branch and bound phase was much faster than before, as expected. After that there is the postprocessing which now makes up about 80% of the 4 minutes it takes to solve my problem. Can anyone tell me what happens in that phase and how I can influence it? From my understanding of integer programming, if the branch and bound phase has found a solution that satisfies my gap settings, there should not be anything left to do except just giving me the solution.

I really appreciate any kind of help with this.

Best regards,
Alex

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