Seek help about formulation of the constraints

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YUNFAN KANG

2022年02月12日 00:45

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I want to write a MIP solver for the max-p-region problem: https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1467-9787.2011.00743.x 

I do not know how I can add this constraint (constraint (4) on page 8, where Ni is a set of integers. Could someone please give me a hint about how to write the addConstrs() for this constraint?

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• 正式なコメント

  

  Simranjit Kaur

  • Gurobi Staff

  2025年11月16日 23:43

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  Jonasz Staszek

  • Community Moderator

  2022年02月12日 09:10

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  Hi Yunfan,

  I assume you use Python API.

  Based on your inputs, I would imagine the following code to work:

  import gurobipy as gp
  
  model = gp.Model()
  
  # define K, C, I and x
  for k in K:
      for c in C:
          for i in I:
              m.addLConstr(
                  x[k, c, i] <= gp.quicksum(x[k, c - 1, j] for j in N[i]),
                  name=f"c_{k}_{c}_{i}",
              )
  
  # alternatively
  m.addConstrs(
      (
          x[k, c, i] <= gp.quicksum(x[k, c - 1, j] for j in N[i])
          for k in K
          for c in C
          for i in I
      ),
      name="c",
  )

   

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