Problem: -(x,x) -> 0() -(x,0()) -> x +(x,y) -> +(y,x) +(0(),x) -> x +(x,0()) -> x +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(y,x)) +(p(x),y) -> p(+(x,y)) +(x,p(y)) -> p(+(y,x)) s(p(x)) -> x p(s(x)) -> x Proof: sorted: (order) 0:-(x,x) -> 0() -(x,0()) -> x 1:+(x,y) -> +(y,x) +(0(),x) -> x +(x,0()) -> x +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(y,x)) +(p(x),y) -> p(+(x,y)) +(x,p(y)) -> p(+(y,x)) s(p(x)) -> x p(s(x)) -> x ----- sorts [0>1, 1>3, 2>3] sort attachment (non-strict) - : 1 x 1 -> 0 0 : 3 + : 2 x 2 -> 2 s : 2 -> 2 p : 2 -> 2 ----- 0:-(x,x) -> 0() -(x,0()) -> x Church Rosser Transformation Processor (kb): -(x,x) -> 0() -(x,0()) -> x critical peaks: joinable Matrix Interpretation Processor: dim=1 interpretation: [0] = 0, [-](x0, x1) = 2x0 + 2x1 + 1 orientation: -(x,x) = 4x + 1 >= 0 = 0() -(x,0()) = 2x + 1 >= x = x problem: Qed 1:+(x,y) -> +(y,x) +(0(),x) -> x +(x,0()) -> x +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(y,x)) +(p(x),y) -> p(+(x,y)) +(x,p(y)) -> p(+(y,x)) s(p(x)) -> x p(s(x)) -> x AT confluence processor Complete TRS T' of input TRS: +(0(),x) -> x +(x,0()) -> x +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(y,x)) +(p(x),y) -> p(+(x,y)) +(x,p(y)) -> p(+(y,x)) s(p(x)) -> x p(s(x)) -> x +(x,y) -> +(y,x) T' = (P union S) with TRS P:+(x,y) -> +(y,x) TRS S:+(0(),x) -> x +(x,0()) -> x +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(y,x)) +(p(x),y) -> p(+(x,y)) +(x,p(y)) -> p(+(y,x)) s(p(x)) -> x p(s(x)) -> x S is linear and P is reversible. CP(S,S) = 0() = 0(), s(y) = s(+(y,0())), p(y) = p(+(y,0())), s(x) = s(+(x,0())), p(x) = p(+(x,0())), s(+(x568,0())) = s(x568), s(+(x570,s(y))) = s(+(y,s(x570))), s(+(x572,p(y))) = p(+(y,s(x572))), s(+(x575,0())) = s(x575), s(+(x577,s(x))) = s(+(x,s(x577))), s(+(x579,p(x))) = p(+(x,s(x579))), p(+(x580,0())) = p(x580), p(+(x582,s(y))) = s(+(y,p(x582))), p(+(x584,p(y))) = p(+(y,p(x584))), p(+(x587,0())) = p(x587), p(+(x589,s(x))) = s(+(x,p(x589))), p(+(x591,p(x))) = p(+(x,p(x591))), +(x592,y) = s(+(p(x592),y)), +(x,x593) = s(+(p(x593),x)), p(x594) = p(x594), +(x595,y) = p(+(s(x595),y)), +(x,x596) = p(+(s(x596),x)), s(x597) = s(x597) CP(S,P union P^-1) = y = +(y,0()), x = +(x,0()), x = +(0(),x), y = +(0(),y), s(+(x626,y)) = +(y,s(x626)), s(+(x628,x)) = +(x,s(x628)), s(+(x631,x)) = +(s(x631),x), s(+(x633,y)) = +(s(x633),y), p(+(x634,y)) = +(y,p(x634)), p(+(x636,x)) = +(x,p(x636)), p(+(x639,x)) = +(p(x639),x), p(+(x641,y)) = +(p(x641),y) CP(P union P^-1,S) = +(x,0()) = x, +(0(),x) = x, +(y,s(x)) = s(+(x,y)), +(s(y),x) = s(+(y,x)), +(y,p(x)) = p(+(x,y)), +(p(y),x) = p(+(y,x)) We have to check termination of S: Matrix Interpretation Processor: dim=1 interpretation: [p](x0) = x0, [s](x0) = x0, [+](x0, x1) = x0 + x1, [0] = 2 orientation: +(0(),x) = x + 2 >= x = x +(x,0()) = x + 2 >= x = x +(s(x),y) = x + y >= x + y = s(+(x,y)) +(x,s(y)) = x + y >= x + y = s(+(y,x)) +(p(x),y) = x + y >= x + y = p(+(x,y)) +(x,p(y)) = x + y >= x + y = p(+(y,x)) s(p(x)) = x >= x = x p(s(x)) = x >= x = x problem: +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(y,x)) +(p(x),y) -> p(+(x,y)) +(x,p(y)) -> p(+(y,x)) s(p(x)) -> x p(s(x)) -> x Matrix Interpretation Processor: dim=1 interpretation: [p](x0) = x0, [s](x0) = x0 + 3, [+](x0, x1) = x0 + x1 + 2 orientation: +(s(x),y) = x + y + 5 >= x + y + 5 = s(+(x,y)) +(x,s(y)) = x + y + 5 >= x + y + 5 = s(+(y,x)) +(p(x),y) = x + y + 2 >= x + y + 2 = p(+(x,y)) +(x,p(y)) = x + y + 2 >= x + y + 2 = p(+(y,x)) s(p(x)) = x + 3 >= x = x p(s(x)) = x + 3 >= x = x problem: +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(y,x)) +(p(x),y) -> p(+(x,y)) +(x,p(y)) -> p(+(y,x)) Matrix Interpretation Processor: dim=1 interpretation: [p](x0) = x0, [s](x0) = x0 + 2, [+](x0, x1) = 4x0 + 4x1 orientation: +(s(x),y) = 4x + 4y + 8 >= 4x + 4y + 2 = s(+(x,y)) +(x,s(y)) = 4x + 4y + 8 >= 4x + 4y + 2 = s(+(y,x)) +(p(x),y) = 4x + 4y >= 4x + 4y = p(+(x,y)) +(x,p(y)) = 4x + 4y >= 4x + 4y = p(+(y,x)) problem: +(p(x),y) -> p(+(x,y)) +(x,p(y)) -> p(+(y,x)) Matrix Interpretation Processor: dim=1 interpretation: [p](x0) = x0 + 4, [+](x0, x1) = 2x0 + 2x1 + 1 orientation: +(p(x),y) = 2x + 2y + 9 >= 2x + 2y + 5 = p(+(x,y)) +(x,p(y)) = 2x + 2y + 9 >= 2x + 2y + 5 = p(+(y,x)) problem: Qed