Iterated invariance principle for random dynamical systems
Davor Dragicevic, Yeor Hafouta
TL;DR
The paper proves a weak iterated invariance principle for a broad class of non-uniformly expanding random dynamical systems in a quenched setting, using a martingale-coboundary decomposition to handle dependence in random environments. It first establishes CLT/LIL-type results for sums along random compositions, then builds a framework for iterated WIP by reducing to martingale limits and coboundary corrections, yielding explicit Brownian limits with possible drift terms. The work further provides a quenched homogenization result for fast-slow systems when the fast component is uniformly expanding, and demonstrates applicability to both uniformly and nonuniformly mixing random maps, including several concrete examples. The methods hinge on transfer operator decay, martingale techniques, and rough-path–type constructions, and are supported by an appendix on ergodicity and technical lemmas.
Abstract
We prove a weak iterated invariance principle for a large class of non-uniformly expanding random dynamical systems. In addition, we give a quenched homogenization result for fast-slow systems in the case when the fast component corresponds to a uniformly expanding random system. Our techniques rely on the appropriate martingale decomposition.
