Re: [Help-glpk] set of sets

[Andrew Makhorin]

> I am writing a timetabling program in GMPL and I #39;d like to
> write some incompatibility constraints of courses generally, e.g. I
> want to say that no more than 1 of {A1, A2, A3} can appear in the same
> slot, and no more than 1 of {B1, B2} can appear in the same slot

> something like.. 

> set incompatitible := (A1, A2, A3) (B1, B2);

> min.....

> s.t. no_incomp{s in SLOTS}: sum{s in SLOTS, i in incomp}
> allocation[slot, course in i] <= 1; /* allocation is binary decision
> variable

> Question: 
> 1. Can I even have a set of sets of different size? 
> 2. How can I express the above? 

> I have read the manual for quite a while but I can #39;t seem to
> find something similar. I #39;d appreciate if you can point to the
> right direction.

You might declare a set (array) of sets as follows:

set incomp[1..N];

where incomp[1] is a first set of incompatible courses, incomp[2] is
a second set, etc., assuming the following initialization in the data
section:

set incomp[1] := A1 A2 A3;
set incomp[2] := B1 B2;
. . .