Re: [Help-glpk] ordered sets query

[Andrew Makhorin]

Friday, October 19, 2007, 4:23:49 PM, you wrote:

> I have a piece of AMPL code I am trying
> to rewrite in MATHPROG that uses ord() 

> subject to g1{k in TT, i in Pat1[k], j in Patt1[k]:ord(i)=ord(j)}:
> -10<=sum{(i,t) in PatP1[k]}
> R[i]*x[i,t]-sum{(j,s) in PatPP1[k]} R[j]*x[j,s] <=10;

> The ord part looks at the ordered set (Pat1[k], Patt1[k]) and
> matches those two set members individually.

You can define parameters which map elements of Pat1 and Patt1 to
their ordinal numbers, e.g.

param ord1{k in TT, i in Pat1[k]};
param ord2{k in TT, i in Patt1[k]};

and then write something like this:

subject to g1{k in TT, i in Pat1[k], j in Patt1[k]:ord1[i]=ord2[j]}:
-10<=sum{(i,t) in PatP1[k]}
R[i]*x[i,t]-sum{(j,s) in PatPP1[k]} R[j]*x[j,s] <=10;