Why "constraint has no bool value (are you trying "lb <= expr <= ub"?)"

Answered

MA MENGYUAN

December 13, 2022 13:38

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mdl.addConstrs(quicksum(x[0,i,k] for i in N) == (y[j,0,k] for j in N) <= 1 for k in K)
mdl.addConstrs(u[i,p,k]-u[j,p,k]+m[p]*x[i,j,k] <= m[p]-q[j,p] for i in V for j in V if i!=j
for k in K for p in P)

My code has this error "constraint has no bool value (are you trying "lb <= expr <= ub"?)"

Can someone help me?

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 13, 2026 01:51

  This post is more than two 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 try Gurobot, our chatbot interface offering instant, expert-level support.
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  Jaromił Najman

  • Gurobi Staff

  December 13, 2022 14:26

  Your first constraint

  mdl.addConstrs(quicksum(x[0,i,k] for i in N) == (y[j,0,k] for j in N) <= 1 for k in K)

  reads \(\sum_{i \in N} x_{0,i,k} = y_{j,0,k} \forall j \in N \leq 1 \forall k \in K\). As you can see there is definitely at least one (in)equality too many.

  For additional details, please refer to the Knowledge Base article Constraint has no bool value (are you trying "lb <= expr <= ub"?).

  Best regards, 
  Jaromił

  Best regards, 
  Jaromił

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  MA MENGYUAN

  December 13, 2022 14:36

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  Dear Jaromil,

  Thanks a lot. 

  Best regards,

  Ma

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