Hi,
This is not really question specific to gecode, but since there are
presumably a lot of constraint-savvy people on this list, I'll ask anyway:
I have a finite set variable X, with domain {0..N-1} (though I could
replace it by an array of booleans if that turns out to be more
convenient). Every element i in the domain of X has a certain weight,
w(i) (which is in the range 0..K; K is typically small). I want to post
the constraint
Y = min_{i in X} w(i) if X is non-empty
0 if X is empty.
Y is used in an expression that is minimised, so upper-bounding it
(which would be simple) is not enough. The best I've been able to come
up with is to write something like
(i in X) & (forall j s.t. w(j) < w(i) : not(j in X)) -> (Y = w(i)).
Does anyone know of a better way to formulate it?
Thanks,
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