Problems implementing the power function

ユーザーの入力を待っています。

Nico T

2025年03月19日 12:51

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Hello, I am currently trying to model the following context in Gurobi.

\(App_{pd}=0.5+0.5(1-S_{pd}^{-p})\)

 

The code of the constraints looks something like this. 

 

help = Model.addVars(P, D, lb=0, ub=gu.GRB.INFINITY, vtype=gu.GRB.CONTINUOUS, name=“help”)
            for p in P:
                for d in D:
                    if d >= min(D):
                        Model.addLConstr(S[p, d] == gu.quicksum(y[p, t] for t in range(D[0], d + 1)), name=f'App_Sum_{p}_{d}')
                        Model.addGenConstrPow(S[p, d], help[p, d], -power,
                                                   name=f“power_cal_{p},{d}”)
                        Model.addLConstr(App[p, d] == base + (1 - base) * (1 - help[p, d]),
                                              name=f'App_det_{p}_{d}')

 

Unfortunately, I always get this IIS:

 

no_treatment_1_-9: w[1,-9] = 0.0

treatment_1_-9: -1.0 x[1,1,-9] + -1.0 x[1,2,-9] + -1.0 x[1,3,-9] + -1.0 x[1,4,-9] + -1.0 x[1,5,-9] + -1. 0 x[1,6,-9] + -1.0 x[1,7,-9] + -1.0 x[1,8,-9] + -1.0 x[1,9,-9] + -1.0 x[1,10,-9] + -1.0 y[1,-9] + w[1,-9] = 0.0

App_Sum_1_-9: -1.0 y[1,-9] + S[1,-9] = 0.0

 

What could be the reason that the model becomes infeasible? Here w[.,.] is binary, as are x[.,.] and y[.,.]. App[.,.] is continuous and App[.,.] is an integer variable. Is the power function possibly not defined?

関連

• General Constraints

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• 

  Marika Karbstein

  • Gurobi Staff

  2025年03月19日 15:31

  This is difficult to analyze. You need to provide more information.
  Setting all variables to 0 in the "IIS" satisfies all constraints. So, this is not an IIS.
  Your addGenConstrPow call does not look suspicious.
  A Minimal Reproducible Example could help.

  
  
  

  0

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