[Bug-glpk] Assertion triggered

[Anders Franzen]

Hi,

I have a small integer programming problem (below in CPLEX format)
which triggers an assertion in version 4.7 of GLPK:

  Assertion failed: x >= lb; file glpmip2.c; line 230

It may take a few minutes on a slower machine (6 minutes on an
Athlon 1.3GHz). The same assertion is also triggered even if
only the constraints r(3), r(6) and r(13) are kept, but it still
takes a while to get there. Strange, since the problem now has a
trivial solution.

Any ideas on what's going on?

---- BEGIN ----

Minimize
 obj: 0 x(1)

Subject To
 r(1): + 1000 x(3) - x(1) <= 0
 r(2): - 1000 x(3) + x(1) <= 999
 r(3): + x(4) + 10000 x(3) - 10 x(1) = 0
 r(4): + 10 x(5) - x(2) <= 0
 r(5): - 10 x(5) + x(2) <= 9
 r(6): + x(7) + 10 x(5) - x(4) - x(2) = 0
 r(7): - x(2) <= 0
 r(8): + x(2) <= 9
 r(9): - x(7) <= 0
 r(10): + x(7) <= 9999
 r(11): + 10 x(8) - x(7) <= 0
 r(12): - 10 x(8) + x(7) <= 9
 r(13): + 10 x(8) - x(7) + x(2) <= -1

Bounds
 x(1) free
 x(2) free
 x(3) free
 x(4) free
 x(5) free
 x(6) free
 x(7) free
 x(8) free

Generals
 x(1)
 x(2)
 x(3)
 x(4)
 x(5)
 x(6)
 x(7)
 x(8)

End
--- END ---

Regards,

/Anders
--
Anders Franzén
address@hidden