Andrew, Thanks for reply. I think I've figured it out.
I've used your example jssp.mod to demonstrate what I'm trying to do. The idea is to provide an index for a set of tuples, in this example for the set of job/machine pairs. This index provides the means to eliminate redundant pairs or disjunctive constraints of the job-shop scheduling problem. For jssp.mod, the result is a reduction of 180 to 90 binary variables, and solution time from 17.5 to 4.99 seconds for solution time. Jeff 2009/12/21 Andrew Makhorin <[email protected]> > > I #39;m working on a scheduling problem in , and would like to add an > > index to each member of a set. That is, if I start with a set A, B, > > C, D, E ..., I #39;d like to end up with a set of tuples (1,A), (2,B), > > (3,C), .... > > > I #39;m still crawling up the GMPL learning curve, but not sure of > > exactly the best way to do this. > > Probably you can use something like this: > > set S; > /* A, B, C, ... */ > > param p{i in S}; > /* p[i] maps i to 1, 2, 3, ... */ > > set T := setof{i in S} (p[i], i); > /* resulting set of doublets (1,A), (2,B), ... */ > >
jssp_JCK.mod
Description: Binary data
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