The HOMFLYPT skein module of $S^1 \times S^2$ via braids

Abstract

In this paper we compute the HOMFLYPT skein module of $S^1 \times S^2\, \cong \, L(0, 1)$, denoted $\mathcal{S}(S^1 \times S^2)$, using braid-theoretic techniques. We extend the Lambropoulou invariant, $X$, for links in the solid torus ST to links in $S^1 \times S^2$, by solving an infinite system of equations of the form $X_{\widehat{a}} = X_{\widehat{bbm(a)}}$, where $bbm(a)$ denotes all possible band moves applied to $a$, for all $a$ in a basis of $\mathcal{S}(ST)$. We show that the free part of $\mathcal{S}(S^1 \times S^2)$ is generated by the empty link, while all other elements are torsion.