  \"Ostlund (2001) showed that all planar isotopy invariants of generic plane
curves that are unchanged under cusp moves and triple point moves, and of
finite degree (in self-tangency moves) are trivial. Here the term "of finite
degree" means Arnold-Vassiliev type. It implies the conjecture, which was often
called \"Ostlund conjecture: "Types I and III Reidemeister moves are sufficient
to describe a homotopy from any generic immersion from the circle into the
plain to the standard embedding of the circle". Although counterexamples are
known nowadays, there had been no (easy computable) function that detects the
difference between the counterexample and the standard embedding on the plain.
However, we introduce a desired function (Gauss diagram formula) is found for
the two-component case.
