'OR' in conditional constraint

Answered

Ying Xue

October 11, 2023 01:16

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I was trying to define a variable x using gurobi julia.

x could either equal to 0 or greater equal to 10.

I tried to use the big-M formulation in this article but seems doesn't work: https://support.gurobi.com/hc/en-us/articles/4414392016529-How-do-I-model-conditional-statements-in-Gurobi-

@variable(model, x >= 0)  
@variable(model, delta, Bin)
@constraint(model, x >= 10-M*(1-delta))

Related to

• Semi-continuous
• Julia

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  Marika Karbstein

  • Gurobi Staff

  October 11, 2023 09:57 Edited

  You need an upper bound on your variable (which can be seen as the big-M). Then you can define \(x\) as a semi-continuous variable in julia, see Constraints · JuMP.
  Or you add the constraints \(x\geq 10\delta\) and \(x\leq M\delta\).

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