The Kauffman bracket skein module of the handlebody of genus 2 via braids

Abstract

In this paper we present two new bases, $B_{H_2}^{\prime }$ and ${\mathcal{B}}_{H_2}$, for the Kauffman bracket skein module of the handlebody of genus 2 $H_2$, KBSM($H_2$). We start from the well-known Przytycki-basis of KBSM($H_2$), $B_{H_2}$, and using the technique of parting we present elements in $B_{H_2}$ in open braid form. We define an ordering relation on an augmented set $L$ consisting of monomials of all different "loopings" in $H_2$, that contains the sets $B_{H_2}$, $B_{H_2}^{\prime }$ and ${\mathcal{B}}_{H_2}$ as proper subsets. Using the Kauffman bracket skein relation we relate $B_{H_2}$ to the sets $B_{H_2}^{\prime }$ and ${\mathcal{B}}_{H_2}$ via a lower triangular infinite matrix with invertible elements in the diagonal. The basis $B_{H_2}^{\prime }$ is an intermediate step in order to reach at elements in ${\mathcal{B}}_{H_2}$ that have no crossings on the level of braids, and in that sense, ${\mathcal{B}}_{H_2}$ is a more natural basis of KBSM($H_2$). Moreover, this basis is appropriate in order to compute Kauffman bracket skein modules of c.c.o. 3-manifolds $M$ that are obtained from $H_2$ by surgery, since isotopy moves in $M$ are naturally described by elements in ${\mathcal{B}}_{H_2}$.

14 pages, 15 figures