MAYBE 0.08/0.17 MAYBE 0.08/0.17 0.08/0.17 Problem: 0.08/0.17 f(s(x),y) -> f(x,s(s(x))) 0.08/0.17 f(x,s(s(y))) -> f(y,x) 0.08/0.17 0.08/0.17 Proof: 0.08/0.17 Open 0.08/0.18 EOF