/* From the book PROLOG PROGRAMMING IN DEPTH
   by Michael A. Covington, Donald Nute, and Andre Vellino.
   Copyright 1988 Scott, Foresman & Co.
   Non-commercial distribution of this file is permitted. */

/* GEO.PL */
/* Sample geographical knowledge base */
 
/* Clause 1 */  located_in(atlanta,georgia).
/* Clause 2 */  located_in(houston,texas).
/* Clause 3 */  located_in(austin,texas).
/* Clause 4 */  located_in(toronto,ontario).
/* Clause 5 */  located_in(X,usa) :- located_in(X,georgia).
/* Clause 6 */  located_in(X,usa) :- located_in(X,texas).
/* Clause 7 */  located_in(X,canada) :-
                                   located_in(X,ontario).
/* Clause 8 */  located_in(X,north_america) :-
                                   located_in(X,usa).
/* Clause 9 */  located_in(X,north_america) :-
                                   located_in(X,canada).
 

