You may wish to check out the (free) books Logic, Programming and Prolog (http://www.ida.liu.se/~ulfni53/lpp/ http://www.ida.liu.se/~ulfni53/lpp/) or Learn Prol

You may wish to check out the (free) books Logic, Programming and Prolog (http://www.ida.liu.se/~ulfni53/lpp/ http://www.ida.liu.se/~ulfni53/lpp/) or Learn Prolog Now! (http://learnprolognow.org http://learnprolognow.org). Personally, I find declarative logic programming to be a great tool in domain analysis -- it's a powerful technique to document and prototype domain rules. I've never used it as an actual business rules engine, but I always feel like I should explore Prolog/Datalog or answer-set programming as a possible solution.