00100	(DE ISWIN (X) (EQUAL X (QUOTE (0 0 -1))))
00200	
00300	(DE ISLOSE (X) (OR (AND (NOT (EQUAL (CAR X) 0))
00400	(GREATERP (CADR X) (CAR X)))
00500	(AND (NOT (EQUAL (CAR X) 3)) (LESSP (CADR X) (CAR X)))))
00600	
00700	(DE SUCCESSORS (X) (PURGE (LIST (LIST 
00800	(DIFFERENCE (CAR X) (TIMES 2 (CADDR X))) (CADR X) 
00900	(MINUS (CADDR X)))
01000	(LIST (DIFFERENCE (CAR X) (CADDR X)) (CADR X) (MINUS (CADDR X)))
01100	(LIST (DIFFERENCE (CAR X) (CADDR X)) (DIFFERENCE (CADR X)
01200	(CADDR X)) (MINUS (CADDR X)))
01300	(LIST (CAR X) (DIFFERENCE (CADR X) (TIMES 2 (CADDR X)))
01400	(MINUS (CADDR X)))
01500	(LIST (CAR X) (DIFFERENCE (CADR X) (CADDR X))
01600	(MINUS (CADDR X))))))
01700	
01800	(DE PURGE (X) (COND ((NULL X) NIL)
01900	((AND (GREATERP (CAAR X) -1) (LESSP (CAAR X) 4)
02000	(GREATERP (CADAR X) -1) (LESSP (CADAR X) 4))
02100	(CONS (CAR X) (PURGE (CDR X)))) (T (PURGE (CDR X)))))