Also, it's worth noting that all three books implement a subset of Prolog (in Lisp). Prolog is another language which sounds really bizarre, but can be incredib

Also, it's worth noting that all three books implement a subset of Prolog (in Lisp). Prolog is another language which sounds really bizarre, but can be incredibly powerful. It's less general purpose than Lisp, though - essentially, it works by searching for answers that fulfill all criteria you specify, backtracking to (lazily) generate alternative answers as needed. It's conceptually really cool, and is great for prototyping certain kinds of problems. Some of the literature is also quite good, particularly _The Art of Prolog_ by Sterling & Shapiro.