A new criterion for knots with free periods

Let $p\geq 2$ and $q\neq 0$ an integer. A knot $K$ in the three-sphere is said to be a $(p,q)$-lens knot if and only if it covers a link in the lens space $L(p,q)$. In this paper, we use the second coefficient of the HOMFLY polynomial to provide a necessary condition for a knot to be a $(p,q)$-lens knot. As an application, it is shown that this criterion rules out the possibility of being $(5,1)$-lens for 80 among the 84 knots with less than 9 crossings.Comment: 14 pages, 1 figur

Skein Algebras of the solid torus and symmetric spatial graphs

We use the topological invariant of spatial graphs introduced by S. Yamada to find necessary conditions for a spatial graph to be periodic with a prime period. The proof of the main result is based on computing the Yamada skein algebra of the solid torus then proving that this algebra injects into the Kauffman bracket skein algebra of the solid torus.Comment: 13 pages, 7 figure