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