YES

1 decompositions
 #1 -----------
   1: -(+(x1,x2)) -> +(-(x1),-(x2))
   2: +(x1,x2) -> +(x2,x1)

@Jouannaud and Kirchner's criterion
--- R
   1: -(+(x1,x2)) -> +(-(x1),-(x2))
   2: +(x1,x2) -> +(x2,x1)

--- S
   1: -(+(x1,x2)) -> +(-(x1),-(x2))
   2: +(x1,x2) -> +(x2,x1)