I tried doing a similar puzzle with Prolog. Formulating it in Prolog took longer than for my wife to do it with graph paper. I suspect I could have done it with pencil and propositional calculus quicker; I had previously done another that way.

The final constraint

None of the 5 persons likes the same drink or cigarrete best or has the same pet as one of his neighbours.

is both the most unrealisitic (wrto Real World) and the one that is hardest to express in Prolog or other LP paradigms.

A reduction-based theorem-prover (as opposed to the unification based one that makes Prolog go) might have a better chance at meeting the rec.puzzles definition of "solving", as opposed to trying by exhaustion.

-- Bill