YES
O(n^2)
TRS:
 {
   f(a(), a()) -> f(a(), b()),
   f(a(), b()) -> f(s(a()), c()),
  f(s(X), c()) -> f(X, c()),
   f(c(), c()) -> f(a(), a())
 }
 Natural interpretation:
  Strict:
   {
     f(a(), a()) -> f(a(), b()),
     f(a(), b()) -> f(s(a()), c()),
    f(s(X), c()) -> f(X, c()),
     f(c(), c()) -> f(a(), a())
   }
  Weak:
   {}
  Interpretation class: deltarestricted
  [c](delta) = + 4 + 0*delta
  [s](delta, X0) = + 0*X0 + 0 + 4*X0*delta + 1*delta
  [b](delta) = + 2 + 4*delta
  [a](delta) = + 0 + 7*delta
  [f](delta, X1, X0) = + 0*X0 + 0*X1 + 0 + 1*X0*delta + 4*X1*delta + 0*delta
  
  s_tau_1(delta) = delta/(0 + 4 * delta)
  
  
  f_tau_1(delta) = delta/(0 + 4 * delta)f_tau_2(delta) = delta/(0 + 1 * delta)
  
  Qed