Wenbo Ma

Hello, I am trying to add constraints but encounter an error that I couldn't figure out how to get around.  m.addConstrs((T @ f_a + M_a * (1 - z_hat[k]) >= eta.loc[k, :].values for k in K)) In my c...

Hi, I have an algorithm which contains a loop. At each iteration, I calculate some parameter values and add a new constraint to the existing model and solve. The way I implement it is: I initiate a...

Hi, I was trying to add a user-cut through callback but encountered an error that I cannot resolve. There was always an GurobiError returned saying 'Variable not in model' due to the last 'model.cb...

I have variable gamma indexed by a two-dimension list base_M (e.g. [1, 1], [1, 2], ..., [20, 2]) gamma = m.addVars(base_M, lb = gamma_lb, ub = gamma_ub, vtype = GRB.BINARY, name = 'gamma') I am won...

Hello, I have a large size MIP model and I could come up with a decent feasible solution (have set it as the MIP start value). In the current Gurobi solution process, the root crossover subprocess ...

Hi, I have a MILP model solved to optimal. In the next step of my project, I plan to fix the values for certain variables in my model, re-assign parameter values based on new data and re-optimize t...

I was solving a large MILP problem. On a Linux server with Gurobi 9.1.2, the solver is always stuck solving the root node LP. However, I didn't have this problem when I tested the same problem on m...

I am on a Linux server with user access (no admin access). I installed python by installing Anaconda and then installed Gurobi use Conda install Gurobi. However, I know there are other versions of ...

I have a large-scale model with 1.7 million rows. My initial test gives me the result that the model is infeasible. I am wondering if there is any function I can use to locate which constraints cau...