ahmad alanaqreh

Hi Jaromil Thanks a lot for your answer, yes that is true, in this case how I can replace the objective function?? should I create a new model with a new objective function or there is a way to do ...

Hi Jarmoil I have the following objective function: model.setObjective(quicksum(x[i, j] * alpha[i] for (i, j) in E if i != s) + quicksum((n * (1 - x[i, j]) - 1) * beta[i, j] for (...

Hi Jaromil, this is just the smallest example I have, the time here is acceptable but when the graph has hundreds or thousands of nodes and edges it really takes a lot of time, there is any part th...

Hi Jaromil  your suggestion kind of works, the problem that by using the x.VarName it takes x,1,11 to be before x,1,2 in the sorted list !!  

Hi Jaromil  I am so sorry if the issue was not clear, let me give more details : I have a model where the variable x is defined as follow : x = {}for (i, j) in E: x[i, j] = model.addVar(vtype=GRB....

Hi Matthias I simply do the following : x = {}for (i, j) in E: x[i, j] = model.addVar(vtype=GRB.BINARY, name="x%d,%d," % (i, j)) or  x = model.addVars(E, vtype=GRB.BINARY, name='x')

Hi Jaromil  That is totally true, moreover, I found that FarkasDual is giving good values but the difference was the sign, I mean if the constraint.FarkasDual is positive  constraint.dunbdd is nega...

Hi Jaromil  No, I am searching for Farkas Dual because the problem is infeasible, this unbdd is used to get the dual of the constraints if the problem infeasible(called "unbounded dual"): in AMPL i...

Hi Jaromil  Thanks for your help, so what  I don't understand how I can get the dual unbounded of a specific constraint for an infeasible model?? in AMPL it is simply : constraint.dunbdd but it is ...

Dear Jaromil  Thank you so much for your help, it's working perfectly :) I have another question if you don't mind, I have a model and I am solving the model if it is infeasible, I want to get the ...