;;;; -*- Mode: Lisp; Syntax: Common-Lisp -*-
;;;; Code from Paradigms of AI Programming
;;;; Copyright (c) 1991 Peter Norvig

(setf start '((c on a) (a on table) (b on table) (space on c)
              (space on b) (space on table)))

(use (make-block-ops '(a b c)))
;;;; -> 18

(search-gps start '((a on b) (b on c)))
;;;; -> ((START)
;;;;     (EXECUTING (MOVE C FROM A TO TABLE))
;;;;     (EXECUTING (MOVE B FROM TABLE TO C))
;;;;     (EXECUTING (MOVE A FROM TABLE TO B)))

(search-gps start '((b on c) (a on b)))
;;;; -> ((START)
;;;;     (EXECUTING (MOVE C FROM A TO TABLE))
;;;;     (EXECUTING (MOVE B FROM TABLE TO C))
;;;;     (EXECUTING (MOVE A FROM TABLE TO B)))