On 5 February 2013 19:29, Michael Hennebry <[email protected]> wrote: >> Except when I tried it didn't work, because the reason GLP_IROWGEN is >> called with the solution to the LP relaxation, at which point you have >> non-integer variables and determining problematic loops isn't >> possible. By the time reason GLP_IBINGO is called it's too late to >> prevent the integer solution being returned, because you can't add >> constraints at that point. > > If you really need integers to do your constraint generation, > add the test to your GLP_IROWGEN routine. > If you do not have integers, do not add any cuts.
Ok, thanks for confirming that that will work. > For the purposes of generating cycle-breaking constraints, > you can probably "round" solution to integer: > Anything >= 1-n**-2 rounds to one, everything else to 0. > n is the size of the largest loop with which you might be concerned. > Any loops found will cut off the current solution. > There are better ways. That might work. I'm afraid about adding too many constraints but perhaps I shouldn't be. Using the cut planes is also an approach to investigate. Thanks for your help. -- Martijn van Oosterhout <[email protected]> http://svana.org/kleptog/ _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
