(DE SUBLIS (S X) (COND ((ATOM X) ((LAMBDA (Z) (COND ((NULL Z) X) (T (CDR Z))))
			(ASSOC X S)))
	(T ((LAMBDA (U V) (COND ((AND (EQ U (CAR X)) (EQ V (CDR X))) X)
			(T (CONS U V))))
		(SUBLIS S (CAR X)) (SUBLIS S (CDR X))))))

(DE ORLIS (P U) (AND (NOT (NULL U)) (OR (P (CAR U)) (ORLIS P (CDR U)))))

(DE ANDLIS (P U) (OR (NULL U) (AND (P (CAR U)) (ANDLIS P (CDR U)))))

(DE MAPCAR2 (FN U V) (COND ((NULL U) NIL) (T (CONS (FN (CAR U) (CAR V))
		(MAPCAR2 FN (CDR U) (CDR V))))))

(DE NTH (U N) (COND ((EQUAL N 1)(CAR U)) (T (NTH (CDR U) (SUB1 N)))))

(DE MAPCHOOSE (PRED FN U) (COND ((NULL U) NIL)
		((PRED (CAR U)) (CONS (FN (CAR U)) (MAPCHOOSE PRED FN (CDR U))))
		(T (MAPCHOOSE PRED FN (CDR U)))))