Cutting planes
Dear community,
I have a question about presolve and cutting planes in gurobi. In the gurobi documentation, the following is stated:
" The idea of cutting planes is that they tighten the formulation by removing undesirable fractional solutions, as in the case of MIP presolve, but that they do this during the solution process and without the undesirable side-effect of creating additional sub-problems (unlike branching). "
From this I understand that cuts in gurobi are generated during the branch and bound (the solution process) and not (solely) in the presolve section.
However, in one of the requests on the forum, the following is stated in an answer:
"Gurobi generates these cuts in the presolved model space. " (https://support.gurobi.com/hc/en-us/community/posts/360057921811-Extract-cutting-planes)
I am therefore a bit lost: where exactly are cutting planes generated? Only in the presolve section, or also dynamically during the branch and bound procedure?
Best regards,
Noortje
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The comment : "Gurobi generates these cuts in the presolved model space. " is referring to the presolved model - which has different rows and columns from the original model.
The cuts generated in branch and bound are cuts on the presolved model, not the original model.
I hope that helps.
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Thank you for your reply, Gwyneth! That clarifies it.
Would you maybe be able to also help me with the following: I understand that it is not possible to extract these cutting planes. However, would it be possible to extract where the cutting planes are generated by the solver? And if so, is there also a way to do this without the use of callback functions?Thank you.
Best,
Noortje
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