MAYBE Problem: g(x) -> h(x,x) s(x) -> h(x,0()) s(x) -> h(0(),x) f(g(x)) -> g(g(f(x))) g(s(x)) -> s(s(g(x))) h(f(x),g(x)) -> f(s(x)) s(0()) -> f(0()) s(s(0())) -> f(s(0())) f(s(0())) -> 0() s(s(s(s(s(s(s(0()))))))) -> f(s(s(0()))) f(s(s(0()))) -> s(s(s(s(s(0()))))) f(s(s(x))) -> h(f(x),g(h(x,x))) Proof: Open