[Bug-glpk] incorrect basis status

[Stefan Vigerske]

Hi,

when running GLPK 4.20 on the attached LP without presolver and letting
it start from the standard basis (not advanced), I get a wrong final basis.

The LP contains a row
sum_{i=1..20} x_i = 1
where the variables x_i do not appear somewhere else in the LP.
(x_i correspond to C00000i in the mps file)

I would expect to have at least one of the x_i in the basis, and that is
also the case when the presolver is used or GLPK starts from the
advanced basis (x_20 gets into the basis). However, when running

glpsol --nopresol --std --mps lp03.mps -o lp03.sol

all variables are reported as NF (see attached solution file).

Best,
Stefan

lp03.mps
Description: application/mps

lp03.sol
Description: Text document