Geodesic graphs for a homotopy class of virtual knots
Abstract
We consider a local move, denoted by λ, on knot diagrams or virtual knot diagrams.If two (virtual) knots K1 and K2 are transformed into each other by a finite sequence of λ moves, the λ distance between K1 and K2 is the minimum number of times of λ moves needed to transform K1 into K2. By Γλ(K), we denote the set of all (virtual) knots which can be transformed into a (virtual) knot K by λ moves. A geodesic graph for Γλ(K) is the graph which satisfies the following: The vertex set consists of (virtual) knots in Γλ(K) and for any two vertices K1 and K2, the distance on the graph from K1 to K2 coincides with the λ distance between K1 and K2. When we consider virtual knots and a crossing change as a local move λ, we show that the N-dimensional lattice graph for any given natural number N and any tree are geodesic graphs for Γλ(K).