Lorenzo Moreschini

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Recent activity by Lorenzo Moreschini Recent activity Votes
  • Lazy constraints and cuts in the same model callback

    Answered

    Let M be the integer programming model I need to implement using Gurobi and let C be a family of cuts I am willing to add dynamically during the resolution.Also, the model M contains an exponential...

  • Adding cuts within Gurobi callback only once.

    Answered

    Reading the Callback Codes documentation, I noticed that when `where == MIPNODE` the MIPNODE_PHASE infomation is available, which is described as follows: Current phase in the MIP solution process...

  • Gurobi performance on virtual machines

    Answered

    Is there any kind of data available about the performance penalties incurred when running Gurobi on a virtual machine with a type 1 hypervisor? Whatever the kind of virtualization, I suppose there ...

  • Gurobi use only one thread

    Answered

    I am running Gurobi 10.03 using the Java API (openjdk 21) to solve a MIP model with 57662 variables and 76414 constraints on a machine with Debian 6.1 and 16 CPUs. As you can see from the attached...

  • Unexpected MIP_SOLCNT value

    Answered

    I am experimenting an unexpected behaviour of the callback value MIP_SOLCNT, which should print the number of feasible solutions found so far (I am solving a MIP problem).As you can see from the lo...

  • GRBCallback.getSolution() for GRBVar[][] array with different inner lengths in Java

    Answered

    I am using the Java API and I am having some troubles with the GRBCallback method double[][] getSolution(GRBVar[][] xvars) documented here https://www.gurobi.com/documentation/9.5/refman/java_cb_ge...

  • Gurobi uses less threads than available after restart

    Answered

    I am writing a program than solves many MIP models simultaneously, equally distributing the number of available threads (virtual cores) among all models. When a model completes its threads are reas...

  • GRBVar objects behaviour (and other questions)

    Answered

    Hi, I have a few questions about Gurobi 9.5 API. I mainly use the Java API, so I will use its syntax in my questions (but sometimes I also use the Python API, so please specify which answers are sp...

  • Add/remove variables/constraints during model optimization

    Answered

    Is it possible to add/remove variables and/or constraints to a model while optimisation is running? If so, is the body of a callback function the right place to do this? Instead, if this is not pos...

  • Should I dispose the original model after model.relax()?

    Answered

    I have built a model with integer variables in Python. If at some point I need the relaxed version of the model and I know that I no longer need the original one, can I (or should I) call dispose()...