MAYBE
0.07/0.18	MAYBE
0.07/0.18	
0.07/0.18	Problem:
0.07/0.18	 plus(x,y) -> plusIter(x,y,0())
0.07/0.18	 plusIter(x,y,z) -> ifPlus(le(x,z),x,y,z)
0.07/0.18	 ifPlus(true(),x,y,z) -> y
0.07/0.18	 ifPlus(false(),x,y,z) -> plusIter(x,s(y),s(z))
0.07/0.18	 le(s(x),0()) -> false()
0.07/0.18	 le(0(),y) -> true()
0.07/0.18	 le(s(x),s(y)) -> le(x,y)
0.07/0.18	 sum(xs) -> sumIter(xs,0())
0.07/0.18	 sumIter(xs,x) -> ifSum(isempty(xs),xs,x,plus(x,head(xs)))
0.07/0.18	 ifSum(true(),xs,x,y) -> x
0.07/0.18	 ifSum(false(),xs,x,y) -> sumIter(tail(xs),y)
0.07/0.18	 isempty(nil()) -> true()
0.07/0.18	 isempty(cons(x,xs)) -> false()
0.07/0.18	 head(nil()) -> error()
0.07/0.18	 head(cons(x,xs)) -> x
0.07/0.18	 tail(nil()) -> nil()
0.07/0.18	 tail(cons(x,xs)) -> xs
0.07/0.18	 a() -> b()
0.07/0.18	 a() -> c()
0.07/0.18	
0.07/0.18	Proof:
0.07/0.18	 Open
0.07/0.19	EOF