ABSTRACT
R otation number is a complete invariant for the classification of plane curves that are equivalent to knot projections on a plane. The rotation
number was introduced by Whitney in 1937 [2]. The same notion corresponding to the rotation number may have been introduced by other authors; however, we quote the fact from Arnold’s book [1] here. Although we do not simply follow the contents of Whitney’s paper, we provide the proof of the classification theorem with respect to the context in this book.
