MAYBE

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

Proof:
 Open