Variables with defined value

Answered

Tobias Gehring

August 10, 2022 17:38

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Hello together,

I have a question regarding the definition range of a variable, and was wondering if you could help me with this. 
In my optimization problem I have defined the variable x as follows: x = m.addVar(lb=1.0, ub=7.0, name="x")

Now I wanted to exclude values via the restrictions so that the variable cannot accept the values 3 and 4, for example. However, inequality conditions do not work like e.g. m.addConstr(4!=x, name = "c2"). 

Is there perhaps a way to specify an exact definition set for the variable?  So that the variable can only take the values 1, 3, 6 and 7 for example?

Thanks a lot in advance.

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 16, 2025 23:31

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  Jonasz Staszek

  • Community Moderator

  August 10, 2022 18:03 Edited

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  Hi Tobias,

  this can be done with a bunch of indicator variables and constraints. Perhaps these two posts (here and here) can serve as a guide.

  Best regards
  Jonasz

   

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  Tobias Gehring

  August 16, 2022 09:34

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  Hi Jonasz,

  thanks for the help i will try to implement this in my model.

  Best regards 
  Tobias 

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