Alessandra,
it is not an unreasonable long time for such a big problem. You can find
problems with much fewer rows and columns that are practically impossible
to solve using branch-and-bound.
The MIP-solver got a big upgrade starting from version 4.9, so if you are
using 4.8 you will most likely not use it (unless you are infact using a
later GLPK but a 4.8-interface, however even then you will not be able to
access lpx_intopt, which is the new solver).
So, start by upgrading the GLPK-version and try the advanced MIP-solver as
a first step.
Good luck!
/Oscar Gustafsson
On Fri, 14 Sep 2007, Alessandra De Luca wrote:
I'm trying to solve a MIP problem with 17575 rows, 14960 column and 1018925
non-zeros but Glpk spend a lot of time to solve it (about 40 minutes)....it's
normal or there is a way to solve the problem quickly by setting some
parameters (for example I've realized that if I set the parameter lpx_k_branch
to 0 the execution time for the same problem become larger than 12 hours)?
In this case what are the parameters I have to set to improve glpk solver and
so to reduce the execution time?
(I'm using glpk from my java code by using Glpk 4.8 java interface).
Thanks
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