If you want to know more about logic programming or about Prolog, there is a nice introduction on the web for you.
Visualization predicates (show variable bindings within Term -- good for feature structures and unification grammars; visualize discourse representation theory (DRT) terms)
Which prolog compiler should I choose? A very quick comparison.
Compatibility layer for SWI, YAP and GNU Prolog.
Beware -- the code here is being used to satisfy specific needs. It may or may not work nicely in your application. I publish this here in order to help you; not to make a statement in favor of the techniques used (or not used!).Keywords: Prolog, SWI-Prolog, YAP Prolog, Source Code