get solution mipsol

Answered

Jose Vindel

April 22, 2020 16:48

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The status of the model I am working on is GRB.INF_OR_UNBD, I am interested in getting the values of my variables so, I tried with callback get solution but I don't seem to get any values for my variables, the lines I get are these,

Solution count 0

Model is infeasible or unbounded
Best objective -, best bound -, gap -

User-callback calls 20, time in user-callback 0.00 sec 

I want the values so I can use lazy cuts, how can I get them?

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  June 23, 2025 03:14 Edited

  This post is more than three 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 why not try our AI Gurobot?.
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  Eli Towle

  • Gurobi Staff

  April 22, 2020 19:43

  Hi Jose,

  Is the model is infeasible? You can try to compute an IIS to determine if this is the case. If the model is infeasible, there are no solutions from which to generate lazy constraints. Additionally, lazy constraints can only reduce the feasible region (which already contains no feasible solutions).

  Thanks,

  Eli

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  Thomas Opfer

  April 22, 2020 20:40

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  If you know bounds for every variable that cannot be exceeded, you could add them to model to resolve the ambiguity between infeasibility and unboundedness. If every variable is bounded, then the model cannot be unbounded. Thus, Gurobi will either find a feasible solution or prove infeasibility.

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  Jose Vindel

  April 22, 2020 22:11

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  Thank you both for your answers!

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