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 (ac): -(x,x) -> 0() -(x,0()) -> x AC critical peaks: joinable AC-KBO Processor: precedence: - > 0 weight function: w0 = 1 w(0) = 6 w(-) = 4 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(+(x562,0())) = s(x562), s(+(x564,s(y))) = s(+(y,s(x564))), s(+(x566,p(y))) = p(+(y,s(x566))), s(+(x569,0())) = s(x569), s(+(x571,s(x))) = s(+(x,s(x571))), s(+(x573,p(x))) = p(+(x,s(x573))), p(+(x574,0())) = p(x574), p(+(x576,s(y))) = s(+(y,p(x576))), p(+(x578,p(y))) = p(+(y,p(x578))), p(+(x581,0())) = p(x581), p(+(x583,s(x))) = s(+(x,p(x583))), p(+(x585,p(x))) = p(+(x,p(x585))), +(x586,y) = s(+(p(x586),y)), +(x,x587) = s(+(p(x587),x)), p(x588) = p(x588), +(x589,y) = p(+(s(x589),y)), +(x,x590) = p(+(s(x590),x)), s(x591) = s(x591) CP(S,P union P^-1) = y = +(y,0()), x = +(x,0()), x = +(0(),x), y = +(0(),y), s(+(x620,y)) = +(y,s(x620)), s(+(x622,x)) = +(x,s(x622)), s(+(x625,x)) = +(s(x625),x), s(+(x627,y)) = +(s(x627),y), p(+(x628,y)) = +(y,p(x628)), p(+(x630,x)) = +(x,p(x630)), p(+(x633,x)) = +(p(x633),x), p(+(x635,y)) = +(p(x635),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, [0] = 0, [s](x0) = x0 + 5, [+](x0, x1) = x0 + x1 + 5 orientation: +(0(),x) = x + 5 >= x = x +(x,0()) = x + 5 >= x = x +(s(x),y) = x + y + 10 >= x + y + 10 = s(+(x,y)) +(x,s(y)) = x + y + 10 >= x + y + 10 = s(+(y,x)) +(p(x),y) = x + y + 5 >= x + y + 5 = p(+(x,y)) +(x,p(y)) = x + y + 5 >= x + y + 5 = p(+(y,x)) s(p(x)) = x + 5 >= x = x p(s(x)) = x + 5 >= 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 + 4, [s](x0) = x0, [+](x0, x1) = 4x0 + 4x1 orientation: +(s(x),y) = 4x + 4y >= 4x + 4y = s(+(x,y)) +(x,s(y)) = 4x + 4y >= 4x + 4y = s(+(y,x)) +(p(x),y) = 4x + 4y + 16 >= 4x + 4y + 4 = p(+(x,y)) +(x,p(y)) = 4x + 4y + 16 >= 4x + 4y + 4 = p(+(y,x)) problem: +(s(x),y) -> s(+(x,y)) +(x,s(y)) -> s(+(y,x)) Matrix Interpretation Processor: dim=1 interpretation: [s](x0) = x0 + 1, [+](x0, x1) = 2x0 + 2x1 orientation: +(s(x),y) = 2x + 2y + 2 >= 2x + 2y + 1 = s(+(x,y)) +(x,s(y)) = 2x + 2y + 2 >= 2x + 2y + 1 = s(+(y,x)) problem: Qed