How do I model if and only if statements in Gurobi

Answered

Anggita Ketlin Bella Pratiwi

• March 26, 2024 06:47

hii, I'm having trouble modeling if and only if statements. I modeled it like the code below

for i in range(I): 
    for j in range(J): 
        m.addConstr((h[j] + eps - M * ( 1 - b) <= g[i]), "bigM_constr1" ) 
        m.addConstr((h[j] + M * b >= g[i]), "bigM_constr2" ) 
        '''
        m.addConstr((b==1) >> (x[i,j] == 1), "indicator_constr1")         
        m.addConstr((b==0) >> (x[i,j] == 0), "indicator_constr2")
        '''
        m.addGenConstrIndicator(b,True , x[i,j], GRB.EQUAL, 1.0)

Why when I run it there is an errorKey : (0.9) ?
Please help me

Related to

• KeyError
• Indicator Constraints

0

• 

  Jaromił Najman

  Gurobi Staff

  • March 26, 2024 08:16

  Hi Anggita,

  We discuss how to debug a key error in the Knowledge Base article Tutorial: Preparing a Minimal Reproducible Example.

  Best regards, 
  Jaromił

  0
• 

  Anggita Ketlin Bella Pratiwi

  • March 26, 2024 14:27

  

  

  Hi, I want to ask more. To describe conditional statements whether there are additional indicator limits besides this

  m.addConstr((b == 1 ) >> (z == w1), name= "indicator_constr1" )
  m.addConstr((b == 0 ) >> (z == w2), nama= "indicator_constr2" )

  0
• 

  Jaromił Najman

  Gurobi Staff

  • March 26, 2024 14:35

  To describe conditional statements whether there are additional indicator limits besides this

  Could you elaborate what exactly you mean by "additional indicator limits"?

  Maybe the Knowledge Base article How do I model conditional statements in Gurobi? can help.

  0

Please sign in to leave a comment.