ce jekl

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Recent activity by ce jekl Recent activity Votes
  • When will gurobi perform another presolving?

    Answered

    I have two "mathematically equivalent" models. The only difference between Model 1 and Model 2 is that Model 1 has 20w redundant constraints more than Model 2.Here is the log for Model 2: ```Gurobi...

  • What is the meaning of parameters in log ?

    Answered

    I just set the Method to 1, and change variable bounds and resolve it several times. And I found in the log:```Gurobi Optimizer version 12.0.2 build v12.0.2rc0 (linux64 - "Ubuntu 22.04.4 LTS") CPU ...

  • Warm-start basis for mip in root relaxation

    Answered

    I am currently developing a set of heuristics that are similar to local branching. After incorporating all the local branching constraints into my model, my approach involves only modifying the con...

  • Pass a gurobi model from c++ to python

    Awaiting user input

    Is it possible to pass the Gurobi model from c++ to python by reference or something like that, instead of writing the model to mps in c++ and reading the file in python? I have a project of which ...

  • pyomo with gurobi feasRelax

    Answered

    I need to use gurobi feasRelaxS, and my model is built in pyomo. Is there a way to use pyomo to solve a feasRelax model?

  • Solution to unbounded problems

    Answered

    If gurobi detects the problem is unbounded, e.g. unbounded LP, what solution will be returned? For example, \[\begin{align}\min \alpha \\ s.t. x \ge 0 \end{align} \] what is the value of \(x\)?

  • Explanation for QP Logging

    Answered

    Is there any explanation for quadratic programming? I don't quite understand the logging of QP. What's the meaning of QLMatrix in the log? I have no coefficient less than 1, why there's a 7e-2 in ...

  • Sign of dual (pi) value

    Answered

    From the online doc, I know the sign of dual depends on the sense of constraints, but I'm confused with the following example: m.addConstr(x <= y)m.addConstr(x - y <= 0)m.addConstr(0 <= y - x)m.add...

  • Can't get constraint, like 0 <= 1, by name

    Answered

    I use model.addConstr(x.sum(i, '*') <= 1, f"constr_{i}") However, if x.select(i, '*') is empty, the constraint cannot be get by name. m = Model()c = m.addConstr(0 <= 1, "123")m.update()assert c is ...