> I've been trying different solvers for my mixed integer programming > problems. For a specific problem (LP file: > http://pastebin.com/3tih0fqg), I get a INTEGER UNDEFINED status with > GLPK. However, I believe the correct status should be no integer > feasible solution which is what I get when I use CBC from COIN-OR. > > The solution output file for this problem is: > > Problem: > Rows: 47 > Columns: 1345 (1344 integer, 1344 binary) > Non-zeros: 1633 > Status: INTEGER UNDEFINED > Objective: OBJ = 0 (MINimum) > > Any clue as to why GLPK is returning an undefined status instead of an > infeasible one for this problem?
This may happen when infeasibility is detected by the mip preprocessor (not by the mip solver), which _erroneously_ does not change the mip solution status, so it remains undefined. In any case, if you see on the terminal something like follows: Preprocessing... PROBLEM HAS NO PRIMAL FEASIBLE SOLUTION it means that no integer feasible solution exists. > > I'm using GLPK version 4.52.1 . I've also got the output from it > (http://pastebin.com/ysQiktir). > _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
