[Help-glpk] Re: integer objective

[Andrew Makhorin]

>If the cost function is known to be integer
>because it is an integral combination of integers,
>will GLPK (MIP and BCS) use this in pruning?

Yes. The mip solver informs about that as follows:

Integer optimization begins...
Objective function is integral
+    29: mip =     not found yet; lp =   2.520571739e+03 (1, 0)
+   137: mip =   3.716000000e+03; lp =   2.520571739e+03 (31, 56)

However, implied integer variables are not recognized.

Starting from the version 4.2 glpk has been provided with a new
component, IOS (Integer Optimization Suite), which replaces BCS, so the
latter will be removed from the package. In IOS also there is a flag to
indicate if the objective is integral.