/* 'simp_list' simplifies a list to its elements */

((simp_list () () )
	(!))
((simp_list C (C) )
	(atomic C))
((simp_list (H|T) L)
	(simp_list H H1)
	(simp_list T T1)
	(append H1 T1 L))

((remdup () ()))
((remdup (H|T) S)
	(member H T)
	(!)
	(remdup T S))
((remdup (H|T) (H|S))
	(remdup T S))

((reverse L RL)
	(revlist L () RL))

((revlist () L L))
((revlist (X|L) L1 L2)
	(revlist L (X|L1) L2))

((append () X X))
((append (X|Y) L (X|T) )
	(append Y L T))

((delete X Y Z)
	(append A (X|B) Y)
	(append A B Z))

((subset _ () ))
((subset S (H|T))
	(member H S)
	(delete H S R)
	(subset R T))

((length L N)
	(len L 0 N)
	(!))

((len () N N))
((len (_|T) K N)
	(sum K 1 M)
	(len T M N))

((member X (X|_) ))
((member X (H|T) )
	(member X T))

/* maxlist returns the max element in a list */

((maxlist (X) X)
	(!))
((maxlist (H|T) X)
	(maxlst (H|T) X H))

((maxlst () N N))
((maxlst (H|T) X S)
	(less S H)
	(!)
	(maxlst T X H))
((maxlst (H|T) X S)
	(maxlst T X S))

((islist (_|_) ))
((islist () ))

((unionc () S S))
((unionc (H ','|T) S R)
	(member H S)
	(!)
	(unionc T S R))
((unionc (H ','|T) S (H ','|R))
	(!)
	(unionc T S R))
((unionc (H) S S)
	(member H S)
	(!))
((unionc (H) () (H))
	(!))
((unionc (H) S (H ','|S) ))

((union () S S))
((union (H|T) S R)
	(member H S)
	(!)
	(union T S R))
((union (H|T) S (H|R))
	(union T S R))