MAYBE
MAYBE
TRS:
 {
     mark(f(X1, X2, X3)) -> active(f(mark(X1), X2, mark(X3))),
               mark(a()) -> active(a()),
               mark(b()) -> active(b()),
               mark(c()) -> active(c()),
     f(X1, X2, mark(X3)) -> f(X1, X2, X3),
   f(X1, X2, active(X3)) -> f(X1, X2, X3),
     f(X1, mark(X2), X3) -> f(X1, X2, X3),
   f(X1, active(X2), X3) -> f(X1, X2, X3),
     f(mark(X1), X2, X3) -> f(X1, X2, X3),
   f(active(X1), X2, X3) -> f(X1, X2, X3),
  active(f(a(), b(), X)) -> mark(f(X, X, X)),
             active(c()) -> mark(a()),
             active(c()) -> mark(b())
 }
 DUP: We consider a duplicating system.
  Trs:
   {
       mark(f(X1, X2, X3)) -> active(f(mark(X1), X2, mark(X3))),
                 mark(a()) -> active(a()),
                 mark(b()) -> active(b()),
                 mark(c()) -> active(c()),
       f(X1, X2, mark(X3)) -> f(X1, X2, X3),
     f(X1, X2, active(X3)) -> f(X1, X2, X3),
       f(X1, mark(X2), X3) -> f(X1, X2, X3),
     f(X1, active(X2), X3) -> f(X1, X2, X3),
       f(mark(X1), X2, X3) -> f(X1, X2, X3),
     f(active(X1), X2, X3) -> f(X1, X2, X3),
    active(f(a(), b(), X)) -> mark(f(X, X, X)),
               active(c()) -> mark(a()),
               active(c()) -> mark(b())
   }
  Fail