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Jaromił NajmanCould you please elaborate on the "impossibility to access reduced cost". The simplex method must update these reduced cost attributes anyway.

Hi Marco and Philip, I have a stupid question. How can you determine the set of J? The variables with integral value in MIPNODE (LP solution) don't immediately become a fixed variable in the subtre...

I thought the same at first, but in my test using c++ api is twice faster than python api (model construction time down from 100s to 50s). Sorry, I can't provide the example since the model is conf...

Sorry, my work procedure is: 1. Data preprocessing in python 2. Model construction in c++ 3. Further process in python From step 1 to step 2, I use pybind11 to pass necessary data to c++. But after...

Thanks a lot!

I think your point is interesting, with name keyword, getConstrByName works ok, however, it doesn't work without the keyword. m = Model()c1 = m.addConstr(0 <= 1, "c1")c2 = m.addConstr(0 <= 1, name=...

Thanks, that matches my experiments. I think it's better to put this on documentation. Although the multiplier for the equality constraint is unbounded, the sign of the multiplier still matters.

Yes, the value of `x` will be the same, but `y` will have the opposite sign. I want to do lagrangian relaxations, so I need to get the dual value and use the dual value as coefficients of the const...

I use lagrangian iteration, which means lagrange multipliers `y` are indeed parameters in the model, which will be updated once we have a new `x`. The only variables are `x` in the model. For examp...

IMO, it's a question about the definition of dual variable in gurobi. People may define the equality constraint `Ax= b` with dual variable `y` in Lagrange function as: `\min c^Tx + y^T(b - Ax)` or ...