English

Perturbing Misiurewicz parameters in the exponential family

Dynamical Systems 2015-03-02 v2

Abstract

In one-dimensional real and complex dynamics, a map whose post-singular (or post-critical) set is bounded and uniformly repelling is often called a Misiurewicz map. In results hitherto, perturbing a Misiurewicz map is likely to give a non-hyperbolic map, as per Jakobson's Theorem for unimodal interval maps. This is despite genericity of hyperbolic parameters (at least in the interval setting). We show the contrary holds in the complex exponential family zλexp(z)z \mapsto \lambda \exp(z): Misiurewicz maps are Lebesgue density points for hyperbolic parameters. As a by-product, we also show that Lyapunov exponents almost never exist for exponential Misiurewicz maps. The lower Lyapunov exponent is negative infinity almost everywhere. The upper Lyapunov exponent is non-negative and depends on the choice of metric.

Keywords

Cite

@article{arxiv.1206.6688,
  title  = {Perturbing Misiurewicz parameters in the exponential family},
  author = {Neil Dobbs},
  journal= {arXiv preprint arXiv:1206.6688},
  year   = {2015}
}

Comments

35 pages. Revised version includes thms about pointwise Lyapunov exponents