Help implementing a weird model notation

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Lorenz Wagner

2023年12月03日 08:48

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Hey guys, I recently came across this model notation and I am having a hard time understanding and implementing it in Gurobi. [\\sum_{i,t:i.GG=1\wedge i.O=b}^{}x_{jit}\ge5 \forall j,b\] How do I "understand" the sum? Do the equations have to be fulfilled for both inidzes or only for t? My try looks like this: for j in J: for b in B: model.addConstr(gp.quicksum(x[j,i,t] for t in T if GG[i] == 1 and O[i] == b for i in I if GG[I] == 1 and O[I] == b) <= 5)

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  Simranjit Kaur

  • Gurobi Staff

  2023年12月04日 02:15 編集済み

  Hi Lorenz,

  The logical operator \(\wedge\) represents conjunction, i.e., the and condition. So, the expression \(\sum_{i,t:i.GG=1\wedge i.O=b}\) means summing over i,t such that i.CG=1 and i.O=b. There are no checks for the index t in this condition.

  The constraint \[\sum_{i,t:i.GG=1\wedge i.O=b}x_{jit} \geq 5 \quad \forall j,b \] can be modelled as

  m.addConstrs((gp.quicksum(x[j,i,t] for i in I for t in T if GG[i] == 1 and O[i] == b) >= 5 for j in J for b in B), name="test")

  Best regards,
  Simran

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