[Help-glpk] Ordered Sets

[yo yo]

Hello,

I would like to know if the symbolic sets are ordered or not.
For instance:

set A;    #is a set of symbols;
Param P{A};

...
s.t. sorted{s in A}: P[s+1]>=P[s];    #s is a symbol within A

#s+1 meaning the next element.

Is there a way to make this work?
Is there a way to designate the first (the last, the nth) element of a set.

If I use a set of couple (symbol, index) a solution can be:
s.t. sorted{(s,i) in A,(nexts,i+1) in A}: P[nexts]>=P[s];

Is there a more elegant solution?

Thanks,
Lionel.




        

        
                
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