Hi,
I have a MIP problem (a simple unit commitment problem) that I try to solve with glpsol (v4.55). The problem with this is that finding the root relaxation takes a long time due to numerical instabilities with default settings.
If I however use the dual simplex method to find the root relaxation (--nointopt and --dual options) there is no problem finding the relaxation. The drawback is that I now don't use the MIP presolver.
Is there a way I can use the dual simplex method for find the root relaxation and use the MIP presolver at the same time? Using the --dual option without the --nointopt does not work.
Daniel Andrén