NO

1 decompositions
 #0 -----------
   1: inv(0()) -> 0()
   2: inv(s(x)) -> p(inv(x))
   3: inv(p(x)) -> s(inv(x))
   4: minus(x,0()) -> x
   5: minus(x,p(y)) -> s(minus(x,y))
   6: minus(x,s(y)) -> p(minus(x,y))
   7: minus(0(),x) -> inv(x)
   8: minus(s(x),s(y)) -> minus(x,y)
   9: minus(p(x),p(y)) -> minus(x,y)
  10: inv(x) -> minus(0(),x)
  11: s(p(x)) -> x
  12: p(s(x)) -> x

unjoinable peak
    s(minus(p(_y26),_y27))
*<- minus(p(_y26),p(_y27)) ->*
    minus(_y26,_y27)