Tobias Achterberg

I suspect that this is a numerical issue. When you fix the bounds of the variables to your solution values, what does Gurobi say at the end about the violations of the solution? Does it report viol...

So, you are interested in why some variables appear with an objective coefficient of 0 in the LP file? The reason is one particular aspect of the LP file format. Namely, if you have variables that ...

This is really strange and seems to point to a bug, either in your code or in ours. Would it be possible to send me the Python code that produces this issue? Ideally, you would first simplify and r...

Just to make sure I understand it correctly: you get these very strange values like 1e+69 or 1e-310 in the model, even though you never added those coefficients in your Python program? My guess is ...

In order to count the number of non-zeros, you would typically introduce binary variables that indicate whether a given variable is 0 or not. So, if you have integer variables x1,...,xn, then you w...

Your expectations are correct. An overall model status of OPTIMAL means that there was at least one feasible scenario, but there can also be infeasible scenarios. Whether a particular scenario is f...

1) Correct, you cannot set variable attributes in a callback. But you can produce the cut "x <= 0" and add this as a user cut. Internally, this will then be converted into a bound change. 2) Yes, i...

Yes, it is not possible to pass an LP basis to a MIP solve. This is mostly because the MIP preprocessing would usually invalidate any warm start basis anyways, because most of the MIP preprocessing...

I would like to investigate. Could you please send me - your original model as *.mps file, - your MIP start as *.mst file or *.sol file, and - your modified model with bounds fixed to the MIP start...

Where do these log files come from? From the feasRelax model?