compute IIS

Answered

Gabriel Pimenta

July 31, 2023 17:09

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What defines the efficiency of computeIIS? Testing my model, for some situations, the IIS is computed adequately, reaching a minimum IIS in a short time, while in others, it doesn't reach the minimum even using more time.

Additionally, in cases where the IIS is not minimal, is the result still useful? From the initial tests, it seemed to help very little, as many restrictions are returned in the IIS.

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 13, 2026 01:39

  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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  David Torres Sanchez

  • Gurobi Staff

  August 01, 2023 11:01 Edited

  Hi Gabriel,

  Our article contains a few more details on how IIS works: How does Gurobi compute the IIS for infeasible models?

  For dealing with the size of the IIS you can actually use an alternative method, model.feasRelax. This is discussed in our article: How do I determine why my model is infeasible? particularly in the "Compute IIS can be computationally expensive for larger models" section.

  Cheers, 
  David

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