a Iond University, Tokyo, Japan b Oyama National College of Technology, Oyama, Tochigi 323-0806, Japan
Abstract:
We give a decomposition formula for the Bartholdi zeta function of a graph G which is partitioned into some irregular coverings. As a corollary, we obtain a decomposition formula for the Bartholdi zeta function of G which is partitioned into some regular coverings.