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[Help-glpk] using lpp_presolve
From: |
Erik Rantapaa |
Subject: |
[Help-glpk] using lpp_presolve |
Date: |
Sun, 6 Jun 2004 16:22:01 -0700 (PDT) |
Hello,
I'd like to use use lpp_presolve to obtain a reduced set of constraints without
solving it. I then would like to output the constraints in terms of the
original
variable names.
For instance, given binary variables x and y, the constraint
s.t. x + y >= 2;
would yield x = 1, y = 1 along with the elimination of x and y in any other
constraints that involve them.
I've tried following the logic in simplex2() in file glplpx6a.c, but I'm
not sure what to do after something like:
LPX* lp = original problem
LPP *lpp = lpp_create_wksp();
lpp_load_orig(lpp, lp);
int ret = lpp_presolve(lpp);
// check value of ret
LPX *prob = lpp_build_prob(lpp);
???
The LPX data structure prob seems to have what I want, although I need to
map the structural variable names back to the ones used in lp.
Does anyone know what to do next?
Thanks,
Erik Rantapaa
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