YES Problem: s(p(x)) -> x p(s(x)) -> x +(x,0()) -> x +(x,s(y)) -> s(+(x,y)) +(x,p(y)) -> p(+(x,y)) +(0(),y) -> y +(p(x),y) -> p(+(x,y)) +(s(x),y) -> s(+(x,y)) Proof: Church Rosser Transformation Processor (critical pair closing system, Thm 2.11): +(x231,p(x230)) -> p(+(x231,x230)) s(p(x234)) -> x234 +(p(x236),x235) -> p(+(x236,x235)) +(x241,s(x240)) -> s(+(x241,x240)) p(s(x244)) -> x244 +(s(x246),x245) -> s(+(x246,x245)) +(x250,0()) -> x250 +(0(),x252) -> x252 critical peaks: joinable Matrix Interpretation Processor: dim=1 interpretation: [+](x0, x1) = x0 + 5x1 + 2, [0] = 1, [s](x0) = x0 + 4, [p](x0) = x0 + 1 orientation: +(x231,p(x230)) = 5x230 + x231 + 7 >= 5x230 + x231 + 3 = p(+(x231,x230)) s(p(x234)) = x234 + 5 >= x234 = x234 +(p(x236),x235) = 5x235 + x236 + 3 >= 5x235 + x236 + 3 = p(+(x236,x235)) +(x241,s(x240)) = 5x240 + x241 + 22 >= 5x240 + x241 + 6 = s(+(x241,x240)) p(s(x244)) = x244 + 5 >= x244 = x244 +(s(x246),x245) = 5x245 + x246 + 6 >= 5x245 + x246 + 6 = s(+(x246,x245)) +(x250,0()) = x250 + 7 >= x250 = x250 +(0(),x252) = 5x252 + 3 >= x252 = x252 problem: +(p(x236),x235) -> p(+(x236,x235)) +(s(x246),x245) -> s(+(x246,x245)) Matrix Interpretation Processor: dim=1 interpretation: [+](x0, x1) = 4x0 + x1 + 2, [s](x0) = x0 + 2, [p](x0) = x0 + 4 orientation: +(p(x236),x235) = x235 + 4x236 + 18 >= x235 + 4x236 + 6 = p(+(x236,x235)) +(s(x246),x245) = x245 + 4x246 + 10 >= x245 + 4x246 + 4 = s(+(x246,x245)) problem: Qed