Universal Vassiliev invariants of links in coverings of 3-manifolds

Abstract

We study Vassiliev invariants of links in a 3-manifold $M$ by using chord diagrams labeled by elements of the fundamental group of $M$. We construct universal Vassiliev invariants of links in $M$, where $M=P^2\times [0,1]$ is a cylinder over the real projective plane $P^2$, $M=\Sigma\times [0,1]$ is a cylinder over a surface $\Sigma$ with boundary, and $M=S^1\times S^2$. A finite covering $p:N\longrightarrow M$ induces a map $\pi_1(p)^*$ between labeled chord diagrams that corresponds to taking the preimage $p^{-1}(L)\subset N$ of a link $L\subset M$. The maps $p^{-1}$ and $\pi_1(p)^*$ intertwine the constructed universal Vassiliev invariants.