> I'm trying to solve a Binary Program (BP) where the generation of > clique inequalities is very important. > GLPK, however, emits the following message at the beginning of the search:
> "The conflict graph is either empty or too big" > In fact, I've noticed that this message is quite frequent in many BPs. > When I use other solver (e.g. COIN) in this instance lots of clique > inequalities are generated. > Why GLPK has this limitation ? Currently the clique cut generator is rudimentary and does not allow processing more than 4000 binary variables; though this limit can be changed, if necessary. > Does it uses a dense matrix for > conflicts ? (it would not be a good option...) Yes, currently the conflict graph is stored in dense format. More efficient representation (a sparse graph plus a union of cliques) is not implemented yet. > Another point is that > the clique separation needs to consider *only* variables which are > active in the current fractional solution (a much smaller set). _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
