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

;;; ==============================

(add-fact '(sub dog animal))
(add-fact '(sub bear animal))
(add-fact '(ind Fido dog))
(add-fact '(ind Yogi bear))
(add-fact '(val color Yogi brown))
(add-fact '(val color Fido golden))
(add-fact '(val latin-name bear ursidae))
(add-fact '(val latin-name dog canis-familiaris))

;;; ==============================

> (retrieve-fact '(sub ?kind animal))
(((?KIND . DOG))
 ((?KIND . BEAR)))

> (retrieve-fact '(and (sub ?kind animal)
                       (val latin-name ?kind ?latin)))
(((?LATIN . CANIS-FAMILIARIS) (?KIND . DOG))
 ((?LATIN . URSIDAE) (?KIND . BEAR)))

> (retrieve-fact '(and (ind ?x bear) (val color ?x ?c)))
(((?C . BROWN) (?X . YOGI)))


> (test-bears)
(1 ENTER INDEX: (SUB BEAR ANIMAL))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (SUB BEAR THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (SUB GRIZZLY THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (SUB POLAR-BEAR THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (SUB BEAR LIVING-THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (SUB GRIZZLY LIVING-THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (SUB POLAR-BEAR LIVING-THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (SUB GRIZZLY ANIMAL))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (SUB POLAR-BEAR ANIMAL))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (IND LARS LIVING-THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (IND HELGA LIVING-THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (IND YOGI LIVING-THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (IND LARS THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (IND HELGA THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (IND YOGI THING))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (IND LARS ANIMAL))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (IND HELGA ANIMAL))
(1 EXIT INDEX: T)
(1 ENTER INDEX: (IND YOGI ANIMAL))
(1 EXIT INDEX: T)
(INDEX)

;;; ==============================