Magnus Mariegaard
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Latest activity by Magnus Mariegaard-
Magnus Mariegaard commented,
Okay thank you a lot for the help Jaromil, it is much appreciated. Your explaination makes a lot of sense. Best regards, Magnus
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Magnus Mariegaard commented,
Hi Jaromil Ahh okay, sorry for the trouble then, my bad then… is there a way to start the program without the lazy constraint for maybe one branching for then to use the lazy constraint after?
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Magnus Mariegaard commented,
Of course, the mdl._x is used to get the relaxed values of the LP relaxation of my MIP problem, and are used as such: def sub_elim(model, where): if where == GRB.callback.MIPSOL: sol = m...
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Magnus Mariegaard commented,
And if it helps, the sub_elim function is in short like the following: def sub_elim(model, where): if where == GRB.callback.MIPSol: Testing and adding the lazy constraints...
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Magnus Mariegaard commented,
I can try to shorten it down to give an example A = list of tuplesx = {}for i,j in A: x[i,j] = mdl.addVar(vtype = GRB.BINARY, name = 'x_%d_%d' & (i,j))#multiple contraints givenmdl.addConstrs(.....
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Magnus Mariegaard commented,
Hi Jaromil My mistake with setting of x[i] value, that is a typo and it is iterated as you suggested. However I have tried to impliment it again, and it seems that the mdl._x = x interfeers with th...
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Magnus Mariegaard created a post,
Using an initial solution while also using lazy constraints
AnsweredI have a optimization problem where I have a variable x, I have a heuristic that give an initial solution that I have set using the x[i].start = init_x[i] To set the initial start for x. However I...
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Magnus Mariegaard created a post,
Understanding the best bound of the MIP
AnsweredHi quick question, in your description of best bound and gap you state that (for a min problem): "Somewhat less obvious is that, at any time during the branch-and-bound search we also have a valid ...
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Magnus Mariegaard commented,
Thank you both for the quick and precise responses, that helped a lot.
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Magnus Mariegaard created a post,
Writing a max function for MTZ constraints for the CVRP
AnsweredHi I am trying to solve some instances of the CVRP where I am trying to incorporate some Miller-Tucker-Zemlin constraints for the capacity. I have the variable \[ u_i \] denoting the load at each c...