The rationality of dynamical zeta functions and Woods Hole fixed point formula

Abstract

For one variable rational function $ϕ\in K(z)$ over a field $K$, we can define a discrete dynamical system by regarding $ϕ$ as a self morphism of $\mathbb{P}_{K}^{1}$. Hatjispyros and Vivaldi defined a dynamical zeta function for this dynamical system using multipliers of periodic points, that is, an invariant which indicates the local behavior of dynamical systems. In this paper, we prove the rationality of dynamical zeta functions of this type for a large class of rational functions $ϕ\in K(z)$. The proof here relies on Woods Hole fixed point formula and some basic facts on the trace of a linear map acting on cohomology of a coherent sheaf on $\mathbb{P}_{K}^{1}$.