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