Robert Hildebrand

Is there a python version of  GRBBinvRowi?  https://www.gurobi.com/documentation/7.5/refman/c_grbbinvrowi.html This is what I want to get access to.   I suppose, if not, I could the B^{-1} matrix b...

1. Thanks.  I didn't know that you could access the presolved model.  That's exciting.   2. Then the question is, if we solve the LP relaxation, is there a way to look at the tabluea.  That is,    ...

  Yeah, MIPFocus =1 doesn't do anything.  The starting solution that I feed it is probably optimal. Sure, I'll try making these lazy constraints.  I'll also try a Lagrangian Relaxation to see if th...

The complicating constraints are actually flow constraints: m.addConstrs(( sum(F[e[0],e[1],j] for e in H.in_edges(i)) - sum(F[a[0],a[1],j] for a in H.out_edges(i)) == X[i,j] for i in V for j in V i...

(That last log is from the original model) I'm surprised that it gets stuck on 3.61 as the best bound that it can find.  

Relaxed meaning I dropped some constraints.   I can send you the whole model and data if you want.   Changed value of parameter MIPGap to 0.05Prev: 0.0001 Min: 0.0 Max: inf Default: 0.0001Changed v...

I also just ran this with a reduced mip gap to 0.01%, which gives the tighter upper bound of about 2.65 Optimal solution found (tolerance 1.00e-03)Best objective 2.649999711392e+00, best bound 2.65...

Here is the log data from the relaxed version of the problem.  I have the best feasible solution I have for the original problem fed into this relaxed version as a MIP start.   Gurobi Optimizer ver...

The problem is phrased as a maximization.   Thus, by "dual bound", I mean an upper bound on the problem.   This is why I used MIPFocus 2 and 3. The solution to the relaxed version of the problem is...

Is there a simple way to load the solution file as an initial starting solution for resolving the MIP later? For instance, if on one run I solve and store the solution model.write('model.sol') can ...