MAYBE

Problem:
 f(true(),x,y) -> f(gt(x,y),x,round(s(y)))
 round(0()) -> 0()
 round(s(0())) -> s(s(0()))
 round(s(s(x))) -> s(s(round(x)))
 gt(0(),v) -> false()
 gt(s(u),0()) -> true()
 gt(s(u),s(v)) -> gt(u,v)

Proof:
 Open