On Realizability Of Gauss Diagrams And Constructions Of Meanders

The problem of which Gauss diagram can be realized by plane curves is an old one and has been solved in several ways. In this paper, we present a direct approach to this problem. We show that needed conditions for realizability of a Gauss diagram can be interpreted as follows "the number of exits = the number of entrances" and the sufficient condition is based on Jordan curve Theorem. We give a matrix approach of realization of Gauss diagrams and then we present an algorithm to construct meanders