Thanks for the tip. Ed: the introduction looks like exactly what I need from the prolog side, last I looked at this stuff in prolog, I only found some proof of

Thanks for the tip. Ed: the introduction looks like exactly what I need from the prolog side, last I looked at this stuff in prolog, I only found some proof of concept/instructive texts using Peano numbers - which works after a fashion, but is slow and painful. There's nothing analogous for datalog or some other minimal, embeddable logic/predicate system?