YES 1 decompositions #0 ----------- 1: s(p(x)) -> x 2: p(s(x)) -> x 3: +(x,0()) -> x 4: +(x,s(y)) -> s(+(x,y)) 5: +(x,p(y)) -> p(+(x,y)) 6: -(x,0()) -> x 7: -(x,s(y)) -> p(-(x,y)) 8: -(x,p(y)) -> s(-(x,y)) @Jouannaud and Kirchner's criterion --- R 1: s(p(x)) -> x 2: p(s(x)) -> x 3: +(x,0()) -> x 4: +(x,s(y)) -> s(+(x,y)) 5: +(x,p(y)) -> p(+(x,y)) 6: -(x,0()) -> x 7: -(x,s(y)) -> p(-(x,y)) 8: -(x,p(y)) -> s(-(x,y)) --- S 1: s(p(x)) -> x 2: p(s(x)) -> x 3: +(x,0()) -> x 4: +(x,s(y)) -> s(+(x,y)) 5: +(x,p(y)) -> p(+(x,y)) 6: -(x,0()) -> x 7: -(x,s(y)) -> p(-(x,y)) 8: -(x,p(y)) -> s(-(x,y))