[Coin-discuss] Cbc 2.2 reports integer-infeasible

[Sebastian Nowozin]

Hello Andrew,

Andrew Makhorin wrote:

> In your mps file some integer columns are not listed in the BOUNDS
> section. Glpk sets default lower and upper bounds of such columns to 0
> and +inf, resp. However, the IBM OSL documentation says:
> 
>         "For non-integer variables, the default bounds on columns are
>         0 and +inf. For integer variables, the default bounds on columns
>         are 0 and 1."
> 
> AFAIK, Cbc uses the latter convention that explains why the results
> are different.

This makes a lot of sense, thanks for the clarification.  The MPS file 
was produced by GLPK 4.27 using

    glpsol --cpxlp test.lp --wmps test.mps --check

If this bound-ambiguity does not exist in the Cplex LP format, would it 
make sense to make the bounds explicit in the MPS file in GLPK MPS writer?

Thanks,
Sebastian