Problem: -(0(),0()) -> 0() -(s(x),0()) -> s(x) -(x,s(y)) -> -(d(x),y) d(s(x)) -> x -(s(x),s(y)) -> -(x,y) -(d(x),y) -> -(x,s(y)) Proof: AT confluence processor Complete TRS T' of input TRS: -(0(),0()) -> 0() -(s(x),0()) -> s(x) d(s(x)) -> x -(s(x),s(y)) -> -(x,y) -(x,s(y)) -> -(d(x),y) -(d(x),y) -> -(x,s(y)) T' = (P union S) with TRS P:-(x,s(y)) -> -(d(x),y) -(d(x),y) -> -(x,s(y)) TRS S:-(0(),0()) -> 0() -(s(x),0()) -> s(x) d(s(x)) -> x -(s(x),s(y)) -> -(x,y) S is linear and P is reversible. CP(S,S) = CP(S,P union P^-1) = -(x236,y) = -(s(x236),s(y)), -(x237,y) = -(d(s(x237)),y) CP(P union P^-1,S) = -(d(s(x)),y) = -(x,y) We have to check termination of S: Matrix Interpretation Processor: dim=1 interpretation: [-](x0, x1) = 2x0 + 2x1 + 1, [d](x0) = 2x0, [0] = 0, [s](x0) = x0 + 7 orientation: -(0(),0()) = 1 >= 0 = 0() -(s(x),0()) = 2x + 15 >= x + 7 = s(x) d(s(x)) = 2x + 14 >= x = x -(s(x),s(y)) = 2x + 2y + 29 >= 2x + 2y + 1 = -(x,y) problem: Qed