Liftings of knots in $S_g\times S^1$ and covering of virtual knots

Abstract

A virtual link diagram is called {\em (mod $m$) almost classical} if it admits a (mod $m$) Alexander numbering. In \cite{BodenGaudreauHarperNicasWhite}, it is shown that Alexander polynomial for almost classical links can be defined by using the homology of the associated infinite cyclic cover. On the other hand, in \cite{NaokoKamada} an infinite family of $m$ fold covering over a virtual knot is constructed so that it is mod $m$ almost classical link for all $m$ by using oriented cut point. In this paper, another way to obtain a family of $m$-fold coverings over a given virtual knots, which are mod $m$ almost classical, by using knots in $S_g\times S^1$.