YES Problem: h(f(f(c())),b()) -> f(h(h(h(c(),h(f(h(c(),f(b()))),a())),b()),c())) c() -> c() f(f(h(h(f(a()),a()),c()))) -> f(h(f(c()),b())) h(f(h(f(b()),h(h(f(h(c(),f(c()))),b()),a()))),h(a(),c())) -> c() Proof: Church Rosser Transformation Processor (no redundant rules): strict: h(f(h(f(b()),h(h(f(h(c(),f(c()))),b()),a()))),h(a(),c())) -> c() f(f(h(h(f(a()),a()),c()))) -> f(h(f(c()),b())) h(f(f(c())),b()) -> f(h(h(h(c(),h(f(h(c(),f(b()))),a())),b()),c())) weak: critical peaks: 0 Closedness Processor (*feeble*): Qed