MAYBE 0.09/0.17 MAYBE 0.09/0.18 0.09/0.18 Problem: 0.09/0.18 sum(0()) -> 0() 0.09/0.18 sum(s(x)) -> +(sum(x),s(x)) 0.09/0.18 sum1(0()) -> 0() 0.09/0.18 sum1(s(x)) -> s(+(sum1(x),+(x,x))) 0.09/0.18 0.09/0.18 Proof: 0.09/0.18 Open 0.09/0.18 EOF