Problem: +(0(),y) -> y +(s(x),y) -> s(+(x,y)) +(x,y) -> +(y,x) Proof: AT confluence processor Complete TRS T' of input TRS: +(0(),y) -> y +(s(x),y) -> s(+(x,y)) +(y,0()) -> y +(y,s(x)) -> s(+(y,x)) +(x,y) -> +(y,x) T' = (P union S) with TRS P:+(x,y) -> +(y,x) TRS S:+(0(),y) -> y +(s(x),y) -> s(+(x,y)) +(y,0()) -> y +(y,s(x)) -> s(+(y,x)) S is linear and P is reversible. CP(S,S) = 0() = 0(), s(x) = s(+(0(),x)), s(+(x208,0())) = s(x208), s(+(x210,s(x))) = s(+(s(x210),x)), s(x) = s(+(x,0())), s(+(0(),x215)) = s(x215), s(+(s(x),x217)) = s(+(x,s(x217))) CP(S,P union P^-1) = y = +(y,0()), x = +(x,0()), s(+(x232,y)) = +(y,s(x232)), s(+(x234,x)) = +(x,s(x234)), x = +(0(),x), y = +(0(),y), s(+(x,x239)) = +(s(x239),x), s(+(y,x241)) = +(s(x241),y) CP(P union P^-1,S) = +(y,0()) = y, +(y,s(x)) = s(+(x,y)), +(0(),y) = y, +(s(x),y) = s(+(y,x)) We have to check termination of S: Matrix Interpretation Processor: dim=1 interpretation: [+](x0, x1) = x0 + 3x1 + 7, [0] = 3, [s](x0) = x0 + 7 orientation: +(0(),y) = 3y + 10 >= y = y +(s(x),y) = x + 3y + 14 >= x + 3y + 14 = s(+(x,y)) +(y,0()) = y + 16 >= y = y +(y,s(x)) = 3x + y + 28 >= 3x + y + 14 = s(+(y,x)) problem: +(s(x),y) -> s(+(x,y)) Matrix Interpretation Processor: dim=1 interpretation: [+](x0, x1) = 2x0 + 4x1 + 7, [s](x0) = x0 + 1 orientation: +(s(x),y) = 2x + 4y + 9 >= 2x + 4y + 8 = s(+(x,y)) problem: Qed