YES

1 decompositions
 #1 -----------
   1: Ap(Ap(Ap(S(),x1),x2),x3) -> Ap(Ap(x1,x3),Ap(x2,x3))
   2: Ap(Ap(K(),x4),x5) -> x4
   3: Ap(I(),x6) -> x6

@Development Closedness
--- R
   1: Ap(Ap(Ap(S(),x1),x2),x3) -> Ap(Ap(x1,x3),Ap(x2,x3))
   2: Ap(Ap(K(),x4),x5) -> x4
   3: Ap(I(),x6) -> x6

--- S
   1: Ap(Ap(Ap(S(),x1),x2),x3) -> Ap(Ap(x1,x3),Ap(x2,x3))
   2: Ap(Ap(K(),x4),x5) -> x4
   3: Ap(I(),x6) -> x6