Retrieve removed variables after presolve

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Xinshuo Yang

2023年03月11日 18:46

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Is there a way to retrieve the removed variables (especially the binary variables) after presolve for MIP? I assume the values of those variables have been determined by the presovle and should be stored somewhere.

 

Thanks,

Xinshuo

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  Simranjit Kaur

  • Gurobi Staff

  2026年11月13日 01:47

  This post is more than two years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum, or try Gurobot, our chatbot interface offering instant, expert-level support.
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  Jaromił Najman

  • Gurobi Staff

  2023年03月13日 15:08

  Is there a way to retrieve the removed variables (especially the binary variables) after presolve for MIP?

  No, it is currently not possible to get particular variables which have been removed in presolve. You could generate the presolved model via the presolve method, compare it to the original model, and try to find which variables might have been deleted or aggregated in the presolve step. Please note that some presolve reduction are non-trivial and there is no necessarily a simple mapping from presolved variables to original variables. You can find more information in the Knowledge Base article How does presolve work?

  Best regards, 
  Jaromił

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