Problem: c() -> c() a() -> f(h(h(f(a()),f(f(c()))),b())) c() -> a() h(c(),f(b())) -> c() Proof: Nonconfluence Processor: terms: h(f(h(h(f(a()),f(f(c()))),b())),f(b())) *<- h(c(),f(b())) ->* f(h(h(f(a()),f(f(c()))),b())) Qed