Maliheh Aramon
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Latest activity by Maliheh Aramon
Maliheh Aramon commented,
Your formulation of using auxiliary variables to translate your model into a form which can be implemented using gurobipy looks fine to me. how to determine if the output solution is correct. T...

Maliheh Aramon commented,
Hi Tycho, Let us define upper bounds \(U_s\) and \(U_p\) for the number of ships and total number of pickups. You would need to use your problem knowledge to come up with a simple heuristic to f...

Maliheh Aramon commented,
Hi Yali, You code snippet is not executable. The are random \(\texttt{return()}\) statements with the function definition being commentedout. As the warning message indicates, the linear part of ...

Maliheh Aramon commented,
Please checkout the article How does presolve work?.

Maliheh Aramon commented,
Hi Tycho, It is not possible to use Gurobi Var objects as indices because a Gurobi Var object does not have any value associated with it until the model is solved. To model the relationship as th...

Maliheh Aramon commented,
Hi, Yes, the \(\texttt{quicksum}\) is a gurobipy global function and the \(\texttt{sum}\) is a python function. The \(\texttt{quicksum}\) is a version of the \(\texttt{sum}\) function and it is fa...

Maliheh Aramon commented,
Thanks for your answer. About question 3, I guess that a QP relaxation just could take excessive long time in the presence of numerical issues, in which case the node processing would be terminate...

Maliheh Aramon commented,
Regarding question 2) No, when solving an MIQP model, either you should use the barrier for all QP relaxations including root and node via setting Method=2 and NodeMethod=2, or all the QP relaxatio...

Maliheh Aramon commented,
Hi, You can define an auxiliary variable \(z_{ik} = x_i \land x_k\, ~~ \forall i, k\). The logical And constraints can be implemented using the Model.addGenConstrAnd() method in Gurobi Python API....

Maliheh Aramon commented,
Hi, You can use the BranchPriority attribute to define a branching priority for the subset of variables you are interested in. The variables with larger branching priority values will take priorit...