MAYBE
MAYBE
TRS:
 {
         mark(f(X)) -> active(f(mark(X))),
         mark(g(X)) -> active(g(X)),
          mark(a()) -> active(a()),
         f(mark(X)) -> f(X),
       f(active(X)) -> f(X),
         g(mark(X)) -> g(X),
       g(active(X)) -> g(X),
  active(f(f(a()))) -> mark(f(g(f(a()))))
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
           mark(f(X)) -> active(f(mark(X))),
           mark(g(X)) -> active(g(X)),
            mark(a()) -> active(a()),
           f(mark(X)) -> f(X),
         f(active(X)) -> f(X),
           g(mark(X)) -> g(X),
         g(active(X)) -> g(X),
    active(f(f(a()))) -> mark(f(g(f(a()))))
   }
  Fail