NO Problem: a() -> a() a() -> h(a(),b()) b() -> h(b(),f(f(b()))) b() -> b() h(b(),h(f(a()),a())) -> a() Proof: Nonconfluence Processor: terms: h(b(),h(f(a()),h(a(),h(b(),f(f(b())))))) *<- h(b(),h(f(a()),a())) ->* h(a(),h(b(),f(f(b())))) Qed