Polynomial-like dynamics of analytic maps
Genadi Levin
TL;DR
We study backward invariant (BI) maps as a natural generalization of polynomial-like maps and prove that a polynomial-like restriction exists for BI maps if and only if there is a completely invariant full compact set $K$ containing the postcritical set $P_g$, with $K$ contained in the intersection of all pullbacks $\cap_{i\ge0} U_{-i}$. This result extends to generalized BI maps where $U_{-1}$ may have multiple Jordan components, yielding a generalized PL restriction with a (potentially disconnected) filled Julia set. The proofs combine complex-analytic techniques, circle-map conjugacies, and expansion arguments to establish a dichotomy: either a PL restriction exists and $K$ captures almost all repelling dynamics, or substantial repelling structure persists near $\partial K$ with no PL restriction. These findings broaden the straightening philosophy beyond classical polynomial-like maps and relate to invariant line fields and renormalization phenomena in holomorphic dynamics.
Abstract
The theory of polynomial-like maps is of fundamental importance in holomorphic dynamics. We study dynamical properties of a larger class of maps. Our main result is that, under some natural conditions, a map of this class has a completely invariant compact set if and only if this set is the filled Julia set of a polynomial-like restriction of the map. We also generalize this result to include maps with non-connected domains of definition.
