Problem: b(w(x)) -> w(w(w(b(x)))) w(b(x)) -> b(x) b(b(x)) -> w(w(w(w(x)))) w(w(x)) -> w(x) Proof: AT confluence processor Complete TRS T' of input TRS: b(w(x)) -> w(w(w(b(x)))) w(b(x)) -> b(x) b(b(x)) -> w(w(w(w(x)))) w(w(x)) -> w(x) T' = (P union S) with TRS P: TRS S:b(w(x)) -> w(w(w(b(x)))) w(b(x)) -> b(x) b(b(x)) -> w(w(w(w(x)))) w(w(x)) -> w(x) S is linear and P is reversible. CP(S,S) = w(w(w(w(b(x73))))) = b(w(x73)), b(w(w(w(b(x74))))) = w(w(w(w(w(x74))))), b(b(x75)) = w(w(w(b(b(x75))))), w(b(x76)) = w(b(x76)), w(w(w(w(w(x77))))) = b(b(x77)), b(w(w(w(w(x78))))) = w(w(w(w(b(x78))))), b(w(x79)) = w(w(w(b(w(x79))))), w(w(x80)) = w(w(x80)) CP(S,P union P^-1) = CP(P union P^-1,S) = We have to check termination of S: Matrix Interpretation Processor: dim=1 interpretation: [b](x0) = x0 + 1, [w](x0) = x0 orientation: b(w(x)) = x + 1 >= x + 1 = w(w(w(b(x)))) w(b(x)) = x + 1 >= x + 1 = b(x) b(b(x)) = x + 2 >= x = w(w(w(w(x)))) w(w(x)) = x >= x = w(x) problem: b(w(x)) -> w(w(w(b(x)))) w(b(x)) -> b(x) w(w(x)) -> w(x) Matrix Interpretation Processor: dim=1 interpretation: [b](x0) = 4x0 + 6, [w](x0) = x0 + 4 orientation: b(w(x)) = 4x + 22 >= 4x + 18 = w(w(w(b(x)))) w(b(x)) = 4x + 10 >= 4x + 6 = b(x) w(w(x)) = x + 8 >= x + 4 = w(x) problem: Qed