Problem: +(0(),y) -> y +(x,0()) -> x +(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: +(0(),y) -> y +(x,0()) -> x +(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:+(0(),y) -> y +(x,0()) -> x +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(x,y)) S is left-linear and P is reversible. CP(S,S) = 0() = 0(), s(y) = s(+(0(),y)), s(x) = s(+(x,0())), s(+(x154,0())) = s(x154), s(+(x156,s(y))) = s(+(s(x156),y)), s(+(0(),x159)) = s(x159), s(+(s(x),x161)) = s(+(x,s(x161))) CP(S,P union P^-1) = y = +(y,0()), x = +(x,0()), x = +(0(),x), y = +(0(),y), s(+(x178,y)) = +(y,s(x178)), s(+(x180,x)) = +(x,s(x180)), s(+(x,x183)) = +(s(x183),x), s(+(y,x185)) = +(s(x185),y) PCP_in(P union P^-1,S) = We have to check termination of S: Matrix Interpretation Processor: dim=1 interpretation: [s](x0) = x0, [+](x0, x1) = x0 + 4x1 + 4, [0] = 2 orientation: +(0(),y) = 4y + 6 >= y = y +(x,0()) = x + 12 >= x = x +(s(x),y) = x + 4y + 4 >= x + 4y + 4 = s(+(x,y)) +(x,s(y)) = x + 4y + 4 >= x + 4y + 4 = s(+(x,y)) problem: +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(x,y)) Matrix Interpretation Processor: dim=1 interpretation: [s](x0) = x0 + 1, [+](x0, x1) = x0 + 2x1 + 5 orientation: +(s(x),y) = x + 2y + 6 >= x + 2y + 6 = s(+(x,y)) +(x,s(y)) = x + 2y + 7 >= x + 2y + 6 = s(+(x,y)) problem: +(s(x),y) -> s(+(x,y)) Matrix Interpretation Processor: dim=1 interpretation: [s](x0) = x0 + 1, [+](x0, x1) = 2x0 + 4x1 + 5 orientation: +(s(x),y) = 2x + 4y + 7 >= 2x + 4y + 6 = s(+(x,y)) problem: Qed