Re: [Help-glpk] Fwd: Suggestions for GLPK

[Joey Rios]

> I'm using the GNU Linear Programming Kit and I need to find a method
> to select a single item from a set, for example the first. In AMPL
> language there are functions like first() or last(), but in GMPL they
> are missing. Can you suggest me a way to solve my problem?
> Thank a lot for your attention. Best regards

There has been some debate on the subject of ordered sets before.  They aren't supported in MathProg.

Check out these threads for reference (which may refer to further threads):

http://lists.gnu.org/archive/html/help-glpk/2008-12/msg00109.html

http://lists.gnu.org/archive/html/help-glpk/2007-04/msg00011.html

You might find the work-around that Andrew posted will suit your needs:

http://lists.gnu.org/archive/html/help-glpk/2006-11/msg00059.html

I've used that before and it worked well for me.

Good luck,

Joey