[Help-glpk] binary variables writing lp format; and MIP bounds

[Brady Hunsaker]

1.  A student I am working with noticed that when writing output in LP
format, only "General" integer variables are specified, even if they are
really binary variables.  Is there a reason for omitting the binary
case?  If not, I'll go ahead and change the code and submit a possible
correction.

2.  IOS seems much better than the previous branch-and-bound solver.  I
would like to improve the LP bound, however.  At present, the LP bound
at the pseudo-root is used.  In fact, the maximum (or minimum) of the LP
bounds at active nodes could be used and reported.  I would like to add
this change as well as including a standard option for specifying an
integrality gap for termination of the algorithm.  Is there any reason
not to do this?

If there's no obvious reason not to, then I'll work on these changes and
send them in,

Brady

-- 
Brady Hunsaker
Assistant Professor
Industrial Engineering
University of Pittsburgh
http://www.engr.pitt.edu/hunsaker/