The replacements of signed graphs and Kauffman brackets of links

Let $G$ be a signed graph. Let $\hat{G}$ be the graph obtained from $G$ by replacing each edge $e$ by a chain or a sheaf. We first establish a relation between the $Q$-polynomial of $\hat{G}$[6] and the $W$-polynomial of $G$ [9]. Two special dual cases are derived from the relation, one of which has been studied in [8]. Based on the one to one correspondence between signed plane graphs and link diagrams, and the correspondence between the $Q$-polynomial of signed plane graph and the Kauffman bracket of link diagram, we can compute the Kauffman bracket of link diagram corresponding to $\hat{G}$ by means of the $W$-polynomial of $G$. By this way we use transfer matrix approach to compute the Kauffman bracket of rational links, and obtain their closed-form formulae. Finally we provide an example to point out that the relation we built can be used to deal with a wide type of link family.