Hello Robin, > I have a MIP, very similar to the sudoku.mod example in the examples/ > directory. MIP optimzers are not fast solvers for constraint programming problems.
To choose the variable glpsol uses the Tomlin-Driebeek heuristic by default, cf. http://opim.wharton.upenn.edu/~guignard/916_2011/papers_to_read/Driebeck_1966_MSc.pdf and * Tomlin J.A. Branch and bound methods for integer and non-convex * programming, in J.Abadie (ed.), Integer and Nonlinear Programming, * North-Holland, Amsterdam, pp. 437-50 (1970). You can influence the branching variable if you use GLPK library and provide a callback function. See gpk-4.47/doc/glpk.pdf Best regards Xypron -------- Original-Nachricht -------- > Datum: Thu, 1 Nov 2012 11:20:24 +1300 > Von: robin hankin <[email protected]> > An: [email protected] > Betreff: [Help-glpk] order restrictions > hello. > > I have a MIP, very similar to the sudoku.mod example in the examples/ > directory. > > It's a 3D binary array. > > Let's say I have three restrictions, A, B, and C. > > A is satisfied 70% of the time and it takes a long long time to evaluate. > B is very similar to A but is satisfied 80% of the time. > C is satisfied 0.0001% of the time and is very very quick. > > A human would ignore A and B, and concentrate on C. When he found a > proposed solution > that satisfies C, he would then check A and B (and if either of these is > not satisfied he would > go back to trawling through C).' > > > How do I tell glpsol this information about the best order to evaluate > A/B/C? Or does it "know"? > > > > > > > -- > Robin Hankin > Uncertainty Analyst > [email protected] _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
