Problem: +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(x,y)) +(x,y) -> +(y,x) Proof: AT confluence processor Complete TRS T' of input TRS: +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(x,y)) +(x,y) -> +(y,x) T' = (P union S) with TRS P:+(x,y) -> +(y,x) TRS S:+(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(x,y)) S is linear and P is reversible. CP(S,S) = s(+(x78,s(y))) = s(+(s(x78),y)), s(+(s(x),x81)) = s(+(x,s(x81))) CP(S,P union P^-1) = s(+(x90,y)) = +(y,s(x90)), s(+(x92,x)) = +(x,s(x92)), s(+(x,x95)) = +(s(x95),x), s(+(y,x97)) = +(s(x97),y) CP(P union P^-1,S) = +(y,s(x)) = s(+(x,y)), +(s(y),x) = s(+(x,y)) We have to check termination of S: Matrix Interpretation Processor: dim=1 interpretation: [+](x0, x1) = 2x0 + 4x1 + 4, [s](x0) = x0 + 1 orientation: +(s(x),y) = 2x + 4y + 6 >= 2x + 4y + 5 = s(+(x,y)) +(x,s(y)) = 2x + 4y + 8 >= 2x + 4y + 5 = s(+(x,y)) problem: Qed