YES(?,O(n^1))
TRS:
 {
              f X -> n__f X,
          f f a() -> c n__f g f a(),
       activate X -> X,
  activate n__f X -> f X
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
                f X -> n__f X,
            f f a() -> c n__f g f a(),
         activate X -> X,
    activate n__f X -> f X
   }
  Natural interpretation:
   Strict:
    {
                 f X -> n__f X,
             f f a() -> c n__f g f a(),
          activate X -> X,
     activate n__f X -> f X
    }
   Weak:
    {}
   Interpretation class: stronglylinear
   [activate](X0) = + 1*X0 + 7
   [a] = + 5
   [n__f](X0) = + 1*X0 + 1
   [c](X0) = + 1*X0 + 3
   [g](X0) = + 1*X0 + 0
   [f](X0) = + 1*X0 + 7
   
   Qed