English

Pointwise convergence on the boundary in the Denjoy-Wolff Theorem

Complex Variables 2007-05-23 v1

Abstract

If ϕ\phi is an analytic selfmap of the disk (not an elliptic automorphism) the Denjoy-Wolff Theorem predicts the existence of a point pp with p1|p|\leq 1 such that the iterates ϕn\phi_{n} converge to pp uniformly on compact subsets of the disk. Since these iterates are bounded analytic functions, there is a subset of the unit circle of full linear measure where they all well-defined. We address the question of whether convergence to pp still holds almost everywhere on the unit circle. The answer depends on the location of pp and the dynamical properties of ϕ\phi . We show that when p<1|p|<1(elliptic case), pointwise a.e. convergence holds if and only if ϕ\phi is not an inner function. When p=1|p|=1 things are more delicate. We show that when ϕ\phi is hyperbolic or type I parabolic, then pointwise a.e. convergence holds always. The last case, type II parabolic remains open at this moment, but we conjecture the answer to be as in the elliptic case.

Keywords

Cite

@article{arxiv.math/0407133,
  title  = {Pointwise convergence on the boundary in the Denjoy-Wolff Theorem},
  author = {Pietro Poggi-Corradini},
  journal= {arXiv preprint arXiv:math/0407133},
  year   = {2007}
}

Comments

11 pages

R2 v1 2026-07-22T17:07:35.743Z