Relating reif predicates to other predicates.

[dougransom]

Is there a reason why there could not or should not exist predicate:

unref_reif(P1, P2)
'''

so that P1(A1, A2, ...AN) holds when P2(A1, A2, ..., AN, T) holds and T is the reified value of P1(A1...AN)?

[bakaq]

I have already asked about this in the past: #2557. I don't think it can be done in general.