On 21 Jun 2011, at 13:51, Johannes Inführ wrote:
> Is it possible in Gecode to channel two SetVarArrays A and B, so that when
> A[3] contains 5, B[5] contains 3?
There is no specialized propagator for this, but you can implement a
decomposition using element intersection constraints:
for (int i=0; i<A.size(); i++) {
SetVar z0(*this, i,i, Set::Limits::min, Set::Limits::max);
element(*this, SOT_INTER, B, A[i], z0);
}
This propagates that the intersection of all B[j] for j in A[i] is z0, which
contains at least i.
Note that the reverse implication is not propagated: if A[3] does not contain
5, then B[5] can still contain 3. You can add
SetVar z1(*this, i,i, Set::Limits::min, Set::Limits::max);
element(*this, SOT_INTER, A, B[i], z1);
inside the loop to get both directions.
Cheers,
Guido
--
Guido Tack, http://people.cs.kuleuven.be/~guido.tack/
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