> glpk and MIPLIB 2003 > MIPLIB 2003 http://miplib.zib.de/
> I compiled the glpk 4.31 with Microsoft Visual Studio 2005. > Glpk can solve manna81.mps of MIPLIB 2003 with #8211;mipgap 1.0 > inabout 37 seconds. #8211;mipgap 0.05 ended with tree is empty after > about 129138 seconds. > The two examples make me wonder how an appropriate mipgap can be > selected. In the first example, --mipgap 1.0 works. In the second > exmple, --mipgap 0.05 could not converge to the psoted solution. Please note that miplib-2003 contains *challenge* mip instances, which are very hard even for much more powerful mip solvers than glpk. If the glpk mip solver cannot find a solution for one or two hours, most probably the instance is hard for it. However, you could try using options '--mir', '--gomory', and/or '--cut' along with '--mipgap', which *sometimes* may significantly reduce the solution time. _______________________________________________ Help-glpk mailing list Help-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/help-glpk