YES
O(n^2)
TRS:
 {
       a__f(X) -> f(X),
  a__f(f(a())) -> a__f(g(f(a()))),
    mark(g(X)) -> g(X),
    mark(f(X)) -> a__f(mark(X)),
     mark(a()) -> a()
 }
 Natural interpretation:
  Strict:
   {
         a__f(X) -> f(X),
    a__f(f(a())) -> a__f(g(f(a()))),
      mark(g(X)) -> g(X),
      mark(f(X)) -> a__f(mark(X)),
       mark(a()) -> a()
   }
  Weak:
   {}
  Interpretation class: deltarestricted
  [mark](delta, X0) = + 1*X0 + 0 + 2*X0*delta + 2*delta
  [a](delta) = + 0 + 0*delta
  [f](delta, X0) = + 1*X0 + 1 + 2*X0*delta + 2*delta
  [g](delta, X0) = + 0*X0 + 0 + 1*X0*delta + 0*delta
  [a__f](delta, X0) = + 1*X0 + 1 + 2*X0*delta + 3*delta
  mark_tau_1(delta) = delta/(1 + 2 * delta)
  
  f_tau_1(delta) = delta/(1 + 2 * delta)
  g_tau_1(delta) = delta/(0 + 1 * delta)
  a__f_tau_1(delta) = delta/(1 + 2 * delta)
  
  Qed