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