NO Problem: c() -> a() b() -> f(h(a(),a())) f(a()) -> b() h(a(),b()) -> a() Proof: sorted: (order-sorted) 0:c() -> a() 1:b() -> f(h(a(),a())) f(a()) -> b() h(a(),b()) -> a() ----- sorts [0>3, 1>2, 2>3] sort attachment (non-strict) c : 0 a : 3 b : 1 f : 1 -> 1 h : 2 x 1 -> 1 ----- 0:c() -> a() Church Rosser Transformation Processor: critical peaks: joinable Qed 1:b() -> f(h(a(),a())) f(a()) -> b() h(a(),b()) -> a() Nonconfluence Processor: terms: h(a(),f(h(a(),a()))) *<- h(a(),b()) ->* a() Qed first automaton: final states: {1} transitions: h(3,2) -> 4* h(6,5) -> 1* a() -> 6,3,2 f(4) -> 5* second automaton: final states: {7} transitions: a() -> 7*