MAYBE

Problem:
 plus(0(),x) -> x
 plus(s(x),y) -> s(plus(p(s(x)),y))
 times(0(),y) -> 0()
 times(s(x),y) -> plus(y,times(p(s(x)),y))
 exp(x,0()) -> s(0())
 exp(x,s(y)) -> times(x,exp(x,y))
 p(s(0())) -> 0()
 p(s(s(x))) -> s(p(s(x)))
 tower(x,y) -> towerIter(x,y,s(0()))
 towerIter(0(),y,z) -> z
 towerIter(s(x),y,z) -> towerIter(p(s(x)),y,exp(y,z))

Proof:
 Open