IIS Variable boundsii

Answered

Iason Liagkas

May 15, 2023 15:16

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Hello people, how can we use the IIS variable bounds to determine infeasibility (if we can)? Should they be the same as what we set in our code in order not to cause any problems?

Kind regards
Iason

Related to

• computeIIS

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  Maliheh Aramon

  • Gurobi Staff

  May 15, 2023 22:49

  Hi Iason, 

  I am a bit confused on what you mean by "IIS variable bounds". Can you please elaborate more on what you mean?

  You need to define the variable bounds when building your model. In case the model is declared to be infeasible, you can then call the method Model.computeIIS() to find an irreducible inconsistent system including a subset of constraints and variable bounds which is infeasible and becomes feasible if one of the constraints or variable bounds is removed. 

  Best regards,

  Maliheh

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  Simranjit Kaur

  • Gurobi Staff

  May 16, 2023 00:31

  Hi Iason,

  Just to add to what Maliheh explained about the irreducible inconsistent system (IIS) in her comment: If you set bounds for a variable in the model, but it appears as free in the IIS, it indicates that the variable's bound does not play a role in making the IIS infeasible.

  Best regards,

  Simran

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  Iason Liagkas

  May 16, 2023 05:39

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  Thank you both!

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