Daniele Patria

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Activity overview

Latest activity by Daniele Patria

  • Daniele Patria created a post,

    The model seems to ignore the added constraints

    Awaiting user input
    1. Community
    2. Algorithms

    I designed an optimization algorithm which is iteratively solving a model, adding a constraint, solving it again, remove the old constraint, add the new one, solve, remove, add... And so on. The is...

    • Daniele Patria
    • 4 followers
    • 1 comment
    • 1 vote

  • Daniele Patria created a post,

    Problems very similar to each other requiring much much different amount of time to be solved

    Answered
    1. Community
    2. Algorithms

    Dear support team, I have implemented an algorithm which iteratively solves Integer (BINARY) Linear Problems with Gurobi. The problems solved by Gurobi are all very similar to each other: they only...

    • Daniele Patria
    • 3 followers
    • 1 comment
    • 0 votes

  • Daniele Patria commented,

    1. Community
    2. Programming
    3. Why is my quadratic expression not convex?

    Dear Matthias,I've been investigating the problem and I finally understood what was happening.A quadratic equality constraint, as you suggested, always takes to a non-convex feasible set (with appr...

  • Daniele Patria commented,

    1. Community
    2. Programming
    3. Why is my quadratic expression not convex?

    Thanks for your answer Matthias.I am not really used to ask for help on communities so I apology for any inconvenient that I am causing. I understood how it should be done now. I'll see if it is th...

  • Daniele Patria commented,

    1. Community
    2. Programming
    3. Why is my quadratic expression not convex?

    What do you mean by "reproducible" here?At this point I think I will ask for permission for posting here all the4 needed files, but I don't know how to do it actually. The constraint is just a quad...

  • Daniele Patria commented,

    1. Community
    2. Programming
    3. Why is my quadratic expression not convex?

    Hi Matthias, one thing I forgot to say: the model has only integer variables.The algorithm I've implemented is made of more than 1 python script. I'll try to do my best posting below the significan...

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    • Daniele Patria
    • Edited
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  • Daniele Patria commented,

    1. Community
    2. Programming
    3. Why is my quadratic expression not convex?

    Additional information: when using an inequality constraint, I am not getting the "nonconvex" error but the non-positive-semidefinite one, that follows gurobipy.GurobiError: Q matrix is not positiv...

  • Daniele Patria commented,

    1. Community
    2. Programming
    3. Why is my quadratic expression not convex?

    Thanks for your reply Matthias.At this point I am a bit confused: I am running the algorithm I've implemented (from which the piece of code I posted is taken) with different datasets. All the attem...

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    • Daniele Patria
    • Edited
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  • Daniele Patria commented,

    1. Community
    2. Programming
    3. Why is my quadratic expression not convex?

    Thanks for your answer Matthias.My explanation wasn't the best... I'll try yo make it simpler so that it's clearer and easier for me to explain: I have a quadratic expression made of only non-nega...

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    • Daniele Patria
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  • Daniele Patria created a post,

    Why is my quadratic expression not convex?

    Answered
    1. Community
    2. Programming

    Hello everybody,I am solving a model with a certain quadratic expression as objective function, than replacing the o.f. with a linear expression and using the previous quadratic one as a constraint...

    • Daniele Patria
    • Edited
    • 3 followers
    • 15 comments
    • 0 votes