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What is the Maximum time gurobi takes to find solution

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3 comments

  • Matthias Miltenberger
    Gurobi Staff Gurobi Staff

    Hi Parijat,

    I don't understand the issue here. Gurobi has not yet found the optimal (integer feasible) solution - that's why there is still a gap of 26.3% reported. You are possibly referring to the solution of the root LP relaxation. This is not the optimal solution to your mixed-integer problem, though.

    Furthermore, the running time presented in your log is far from "long" for such a problem. Keep in mind that you are also including quadratic and general constraints, so your problem is even more difficult to solve than a "simple" MIP which is already NP-hard. It is not possible to specify a solving time for any given instance. There are tiny models that may take days to solve while you can solve instances with millions of variables in a few seconds.

    Cheers,
    Matthias

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  • Parijat Mitra
    Gurobi-versary
    Conversationalist
    Investigator

    Thanks for your response. Can you please help me understand what the gap is or any relevant article explaining the gap and root relaxation?

    In case if it takes days to solve a problem, approximately how many days it may take? I know It depends on the nature and complexity of the problem but I just wanted to know an approximated value if it is a medium complexed problem??

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  • Matthias Miltenberger
    Gurobi Staff Gurobi Staff

    Hi Parijat,

    This page is a pretty good introduction to MIP solving and explains the meaning of the gap among other core components:

    Mixed-Integer Programming (MIP) - A Primer on the Basics - Gurobi

    Concerning your question about the expected time to optimality: there is no hope of giving a useful and reasonable estimate. This is different for a set of very similar models; here we can expect (but not guaranteee!) a similar time to optimality.

    I hope this answers your question.

    Cheers,
    Matthias

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