Logic programming.
I'm going to collect a number of pointers and pages under here devoted to various aspects of logic programming.
At the moment, this is a little sparse, but things should improve quickly (work schedule permitting, of course).
Yep, a hideous hack that's kind of got a life of its own these days.
The latest version of the interpreter can always be found at http://ioctl.org/logic/prolog-latest - which should be used for external references.
The history of the interpreter is now a separate document.
These days the kids are all about the licenses. I typically get a request or two every year from a keen undergrad who wants to turn this into something interesting. Consider this code to be under a two-clause (non-advertising) BSD-style license.
Having said that... I'm always interested to hear what people are up to with this, so if you feel keen or want a natter, drop me a line: logic@ioctl.org. I think that ideas are more important than kudos, but if you want to credit then I won't blush (and I'm sure my employer at the time I wrote this, the University of Bristol, wouldn't mind you mentioning them).
Good luck!