note larsen [knobunc]'s reply is good. Check [cpan://Language::Prolog] As far as I know, it is currently a beta version.<br> But, if you want to <i>"reinvent the wheel"</i>, you should consider reading something on the following topics: <ul> <li>Propositional logic <li>Predicate logic <li>Herbrand's Theory <li>Godel-Herbrand-Skolen Theorem <li>Resolution and Robinson's Algorithm <li>Horn Clause Programs <li>Prolog </ul> You can check them in that order :)<br> Logic programming slogan <i>"I tell you what I know and what I'd like to know, without telling you how"</i> showed its practical unapplicability over the years: every logic programming language includes extralogic operators, such as <i>cut</i>, that introduce elements of imperative programming in the language (<i>"I tell you what I know and what I'd like to know, without telling you how... Well, I will help you a bit"</i>).<br> Despite of their impure nature, logic programming languages are very interesting and I think they're worth studying. 71319 71319