MAYBE 50.13/20.12 MAYBE 50.13/20.12 50.13/20.12 Problem: 50.13/20.12 a(a(b(b(x1)))) -> b(b(b(a(a(a(x1)))))) 50.13/20.12 a(x1) -> x1 50.13/20.12 50.13/20.12 Proof: 50.13/20.12 Open 50.13/20.12 EOF