Topological Representations of Free Numerical Semigroups via Iterated Torus Knots

Abstract

In this paper we will associate a family $\{K_1,\dots ,K_l\}\subset {\mathbb{S}}^3$ of iterated torus knots to a given free numerical semigroup. We will describe the fundamental group of the knot complement of each knot of the family. Finally, we will show that all knots in the family have same Alexander polynomial and it coincides (up to a factor) with the Poincaré series of the free numerical semigroup. As a consequence, we will provide families of iterated torus knots with the same Alexander polynomial of an irreducible plane curve singularity but which are non-isotopic to its associated knot.

V2: typos corrected, to appear in Res. Math. Sci. V1:15 pages, comments are very welcome