_The Craft of Prolog_ has a lot of good bits, but is written in response to something less readily available, so its organization seems a bit weird. I also rec

_The Craft of Prolog_ has a lot of good bits, but is written in response to something less readily available, so its organization seems a bit weird. I also recommend the hell out of _The Art of Prolog_. Have done so here, many times. Also: Prolog systems with constraint extensions are MUCH more powerful. SWI Prolog (http://www.swi-prolog.org/ http://www.swi-prolog.org/) and GNU Prolog (http://www.gprolog.org/ http://www.gprolog.org/) are both good.