Strong periodicity of links and the coefficients of the Conway polynomial

Abstract:

Przytycki and Sokolov proved that a three-manifold admits a semi-free action of the finite cyclic group of order $p$ with a circle as the set of fixed points if and only if $M$ is obtained from the three-sphere by surgery along a strongly $p$-periodic link $L$. Moreover, if the quotient three-manifold is an integral homology sphere, then we may assume that $L$ is orbitally separated. This paper studies the behavior of the coefficients of the Conway polynomial of such a link. Namely, we prove that if $L$ is a strongly $p$-periodic orbitally separated link and $p$ is an odd prime, then the coefficient $a_{2i}(L)$ is congruent to zero modulo $p$ for all $i$ such that $2i<p-1$.