[Help-glpk] using lpp_presolve

[Erik Rantapaa]

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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