David Torres Sanchez

Hi Yunzhuang, This happens because the duals for some of the nodes are non-zero. This is just because the gap between the primal and dual has not been closed. Having a column not entering the basis...

Hi Yunzhuang,This is expected behaviour in column generation.In your case, it may happen that using the colourings already produced, all the vertices are covered and the entering column (even thoug...

Hi Jiajie,\( \texttt{GRB.Callback.MIP_NODCNT} \) is just a constant (with value 5005). The correct way to query this attribute is: nodecnt = model.cbGet(GRB.Callback.MIP_NODCNT) Please see the Pyth...

Hi Elina,Glad it worked. Of course, from the Python Callbacks section: If you would like to pass data to your callback function, you can do so through the Model object. For example, if your progra...

Hi Elina,The correct syntax to obtain the runtime in a callback is: runtime = model.cbGet(GRB.Callback.RUNTIME) As shown in the Callback Codes page, this attribute is available everywhere except wh...

Hi Yansong,It appears we are in the case that Marika described. The solver finds the optimal solution very fast (<7s) "before n solutions are found, Gurobi continues in order to find additional, hi...

Hi Yansong,It does work, in the sense that it does not produce an error when used at the same time. In this case, the solver will not terminate until a solution of MIPGap lower than 0.05% is found ...

Hi Yu,This also works! Just replace \(\texttt{a}\) with your value. Best,David

Hi Moe,I think any value greater than than FeasiblityTol (tolerance for constraints) makes sense to me: i.e. anything \(>\texttt{1.0e-6}\), otherwise equality will be accepted as a feasible constr...

Hi Yu,For this purpose, you need several auxiliary variables. Edit: I missed one side of the implication. A continuous variable to represent the difference \(\texttt{y} =\texttt{a}-\texttt{b}\); A...