YES
O(n)
TRS:
 {   f(X, X) -> c(X),
  f(X, c(X)) -> f(s(X), X),
  f(s(X), X) -> f(X, a(X))}
 Natural interpretation:
  Strict:
   {   f(X, X) -> c(X),
    f(X, c(X)) -> f(s(X), X),
    f(s(X), X) -> f(X, a(X))}
  Weak:
   {}
  Interpretation class: stronglylinear
  [c](X0) = + 1*X0 + 2
  [s](X0) = + 1*X0 + 1
  [a](X0) = + 1*X0 + 0
  [f](X1, X0) = + 1*X0 + 1*X1 + 3
  
  Qed