Starlog

The University of Waikato continues to develop really interesting text and semantic web projects.

Starlog is like Prolog, but:

* Starlog is purely declarative: there are no "side-effects." This makes it easer for tools to verify, analyse and optimise Starlog programs.
* Starlog has the added capability of explicitly representing time (and thus state changes).
* Starlog's basic execution mechanism is bottom-up, like most expert systems.

http://www.cs.waikato.ac.nz/Research/starlog/index.html