TRS:
 {   a__f(X) -> g(h(f(X))),
  mark(f(X)) -> a__f(mark(X)),
  mark(g(X)) -> g(X),
  mark(h(X)) -> h(mark(X)),
     a__f(X) -> f(X)}
 LMPO:
  Quasi-Precedence:
  mark > a__f
  empty
  
Normal:
   pi(mark) = [1]
  
Safe:
   pi(a__f) = [1]
  
Predicative System:
   {    a__f(;X) -> g(h(f(X;););),
    mark(f(X;);) -> a__f(;mark(X;)),
    mark(g(X;);) -> g(X;),
    mark(h(X;);) -> h(mark(X;);),
        a__f(;X) -> f(X;)}
  

   
  

  Qed