[Help-glpk] Rewriting AMPL ordered set

[Joey Rios]

Hello,

I am trying to port an AMPL model over to GLPK.  My model has ordered sets.

Searching through these help archives I found Andrew's work around for ordered sets:

set S;
param ref{i in 1..card(S)}, symbolic, in S;
param a{S};
# now a[ref[i]] refers to the ith element of S.

OK, most of that makes sense to me (except the symbolic part... if anyone can explain that in this context, it would be a bonus!).

Now in my model, the problem is my set is two-dimensional.  It looks like this:

set FP {FLIGHTS} ordered within SECTORS;

Where FP is a flight plan and is inherently ordered.  Basically, there are x FPs which are ordered lists of SECTORS (where 'x' is the number of flights).  The length of the FPs is not constant.

So my question is how the syntax would look for this in GLPK?  Everything I try is wrong.  I'm not the best AMPL coder, so this is abstracting things a too far for me.  Hopefully there is a simple-ish solution?  If any further information from me is helpful, just let me know.  Any advice/guidance appreciated.

Thanks.

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