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