How to use computeIIS to find the constraint or the bound that is the source of the infeasibility?

Answered

Hussein Sharadga

December 28, 2022 15:55

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After I use the following command:

m.computeIIS()
m.write("m.ilp")

how to figure out which constraint was the source of the problem? Please see the lip file below: I have a big model and I even do not know where the number 0.0183 comes from

 

Thanks,

Hussein

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 13, 2026 01:50

  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.
• 

  Jonasz Staszek

  • Community Moderator

  December 28, 2022 16:21

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  Hi Hussein,

  the bound could be due to the presolve - Gurobi might have implied it from the other constraints in your model.

  I recommend that you specify a name for each of your constraints (as described in the documentation). You will then be able to identify the constraint which causes the trouble.

  Best regards
  Jonasz

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