The important thing to remember about non-Prolog "Prolog engines" (which I think Pico's "Pilog" is), is that for large applications and data sets, generally for

The important thing to remember about non-Prolog "Prolog engines" (which I think Pico's "Pilog" is), is that for large applications and data sets, generally for anything non-trivial, you need an industrial Prolog implementation for it to be fast. Tiny Prologue-style "engines" can be fun and educational, but they are not a substitute for actual Prolog.