Alexia Payan
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Activity overview
Latest activity by Alexia Payan-
Alexia Payan created a post,
MIP gap
AnsweredHello All, I have a multi-objective hierarchical optimization problem with about 450,000 variables (integer) and 355,000 constraints. After about 11 hours, the MIP gap for the first objective is 10...
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Alexia Payan commented,
Hello Matthias, Thank you for your help. I am aware of the RelTol parameter for a hierarchical optimization but my rationale is as follows: When optimizing the first objective, I am adding a penal...
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Alexia Payan created a post,
Hierarchical optimization and RelTol
AnsweredHello, I am trying to maximize the revenues from building various products while minimizing the number of machines used to make those products (i.e. increase the utilization of these machines). The...
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Alexia Payan commented,
Hello Silke, I have a question regarding the use of the max_ function. I noticed that using it slows down the optimization somewhat. Is this because it is technically not a linear constraint? Have ...
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Alexia Payan created a post,
Very slow hierarchical objective optimization
AnsweredI a considering a hierarchical objective optimization. The first objective already takes a long time to "solve" to a given gap, say 3%. When adding the second objective, the runtime is increased b...
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Alexia Payan commented,
Hello Juan, Thank you for your reply. Regarding both the "cutoff" case and the "infeasible" case, can I still trust the "optimal" solution that is being provided by the optimizer? Also, does this ...
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Alexia Payan created a post,
Cutoff and optimal solution
AnsweredHello All, I get the following output from my model solve: What does the current node "cutoff" objective mean? I still get an optimal solution printout after this happens with a gap of 11.1% corre...
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Alexia Payan commented,
Hello Jaromil, Thank you for your reply. This prints the relaxed solution for the current node being explored but this does not necessarily corresponds to the Best Bound solution. What I am looking...
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Alexia Payan created a post,
Printing best bound solution for MIP problem
AnsweredHello All, Is it possible to print the LP solution corresponding to the best bound objective value at a given time during the optimization, for example when an integer solution to the MIP is found?...