Re: [Help-glpk] information on presolve results

[Andrew Makhorin]

> Is there a way to get information from the presolve routines why
> certain rows / columns can be eliminated from the model?

> My LP problems only have continuous variables.

The lp presolver (see the module glplpp) keeps all information about
applied transformations in an internal stack, however, this information
is not intended to be used out of the lp presolver. Besides, it would be
problematic to analyze it adequately due to its derivative nature. For
example, some column may be eliminated, because other column in the same
row was fixed by its reduced costs obtained from other row that made the
former column an implied slack variable; i.e. there may not be a clear
reason why this or that column has been removed.

For which purpose do you need to obtain such information?