NO

1 decompositions
 #0 -----------
   1: +(0(),0()) -> 0()
   2: +(s(x),y) -> s(+(x,y))
   3: +(x,s(y)) -> s(+(y,x))

unjoinable peak
    s(s(+(_y8,x)))
*<- +(s(x),s(_y8)) ->*
    s(s(+(x,_y8)))