Mario Ruthmair

Hi Florian, Just to be sure, are you also adding the same type of cuts as user-cuts in a MIPNODE callback (to strengthen the bounds)?If yes, can you also reproduce the issue when adding all cuts of...

You need to at least introduce variables that represent the arrival or departure time at some customer. Those need be bounded by the time window and linked to the x_ijk variables. A similar model c...

But if depart and arrival are no variables but constants what exactly is the sense of the constraints your are building with them in function depart_arrival()? Did you follow the guidelines in the ...

Hi Giorgos, To find the cause for infeasibility in general, here are a few suggestions: Write out the model to an LP file with model.write("model.lp") and look at the actually created variables an...

Hi Iason, A Benders decomposition algorithm in Gurobi is basically just a branch-and-cut algorithm where you add Benders cuts in lazy-constraint and/or user-cut callbacks. So you can use any exampl...

Hi Jin, Since it is usually not allowed to access the memory of a different process, here are some suggestions: If you have enough memory, you could create a RAM-disk in your operating system, i.e...

Hi, The issue here is that gp.max_() requires a list of variables (and an optional constant).You need to introduce additional helper variables that are set equal to the term in your max-function. T...

Hi Giorgos, What exactly do you mean with debugging stucks forever? Do you refer to the running time of the solver?Note that you are modeling some VRP with time windows with 100 customers. This siz...

Hi Julie, You could enforce an order for bins to be used in the sense that bin i+1 is only allowed to be used if bin i is already used: model.addConstrs( y[i+1] <= y[i] for i in range(UB-1), name="...

As the first warning says, you could try parameter NumericFocus=1 (or 2, 3). But in general you might work on scaling the coefficients to obtain smaller ranges, as also mentioned in the numerics gu...