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

> (test-index)
((#1=(P A B)
  #2=(P A C)
  #3=(P A ?X)
  #4=(P B C)
  #5=(P B (F C))
  #6=(P A (F . ?X)))
 #(#(NIL NIL (P (6 #6# #5# #4# #3# #2# #1#)) (0))
   #(#(NIL NIL (B (2 #5# #4#) A (4 #6# #3# #2# #1#)) (0))
     #(#(#(NIL NIL (F (2 #6# #5#)) (0))
         #(#(NIL NIL (C (1 #5#)) (0))
           #(NIL NIL NIL (0)) NIL (1 #6#))
         (C (2 #4# #2#) B (1 #1#))
         (1 #3#))
       #(NIL NIL NIL (0))
       NIL (0))
     NIL (0))
   NIL (0)))

> (fetch '(p ? c))
(((P B C) (P A C))
 ((P A ?X)))
3

> (fetch '(p ?x c))
(((P B C) (P A C))
 ((P A ?X3408)))
3

> (retrieve '(p ?x c))
(((?X3408 . C) (?X . A))
 ((?X . A))
 ((?X . B)))

> (retrieve-matches '(p ?v c))
((P A C) (P A C) (P B C))

> (retrieve-matches '(p ?w (?fn c)))
((P A (?FN C)) (P A (F C)) (P B (F C)))