Many thanks to gawrilow and joswig.

@joswig: I really appreciate your detailed answer; it helped me a lot in understanding what's going on.

Hi, I am trying to perform a "projection" operation on a polytope with 9 0-1 variables and 9 nonnegative continuous variables. This is the set of qualities and inequalities that form the feasible region of a well-known mixed-integer program, which is attached to this message. To obtain the...