[Help-glpk] determining fixed variables

[Erik Rantapaa]

I was wondering how I could use GLPK to determine
the variables (if any) whose values are fixed by the
constraints.

For example, given the problem:

maximize a
subject to:
 a + b = 1
 a + b + c = 1

I'd like to deduce that c = 0.

On the MIP side, given the binary ILP problem:

maximize ...
subject to:
  a + b + c = 2
  a + b + d = 1

is it possible for GLPK to deduce that d = 0?

Is it possible to find all fixed variables for an LP
problem? for an MIP problem?

Thanks,

Erik Rantapaa



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