TRS:
 {  f(n__f(n__a())) -> f(n__g(f(n__a()))),
               f(X) -> n__f(X),
                a() -> n__a(),
               g(X) -> n__g(X),
  activate(n__f(X)) -> f(X),
   activate(n__a()) -> a(),
  activate(n__g(X)) -> g(X),
        activate(X) -> X}
 Fail