; Name:		Christopher Higginbotham
; Date:		16 September 1999
; Class:	CSCI 322

; MYUNION
(defun MYUNION (list1 list2)
	(if (not (member (first list1) list2 :TEST #'EQUAL))
		(setf list2 (cons (first list1) list2))
		NIL
	)
	(if (eq (rest list1) 'nil)
		list2
		(MYUNION (rest list1) list2)
	)
)

; MYINTERSECTION
(defun MYINTERSECTION (list1 list2)
	(cond 
		(
			(member (first list1) list2 :TEST #'EQUAL) 
			(cons (first list1) (MYINTERSECTION (rest list1)
list2))
		)
		(
			(not (eq list1 'nil)) 
			(MYINTERSECTION (rest list1) list2)
		)
	)
)


; MYINTERSECTP
(defun MYINTERSECTP (list1 list2)
	(if (not (member (first list1) list2 :TEST #'EQUAL))
		(if (not (eq (rest list1) 'nil))
			(MYINTERSECTP (rest list1) list2)
			NIL
		)
		T
	)
)

; MYSAMESETP		
(defun MYSAMESETP (list1 list2)
	(if (member (first list1) list2 :TEST #'EQUAL)
		(progn
			(setf list2 (remove (first list1) list2))
			(setf list1 (remove (first list1) list1))
			(if (eq list1 'nil)
				(if (eq list2 'nil)
					T
					NIL
				)
				(MYSAMESETP list1 list2)
			)
		)
		NIL	
	)
)