Lower bounds for non-Archimedean Lyapunov exponents
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- by Kenneth Jacobs PDF
- Trans. Amer. Math. Soc. 371 (2019), 6025-6046 Request permission
Abstract:
Let $K$ be a complete, algebraically closed, non-Archimedean valued field, and let $\mathrm {\mathbf {P}}^1$ denote the Berkovich projective line over $K$. The Lyapunov exponent for a rational map $\phi \in K(z)$ of degree $d\geq 2$ measures the exponential rate of growth along a typical orbit of $\phi$. When $\phi$ is defined over $\mathbb {C}$, the Lyapunov exponent is bounded below by $\frac {1}{2}\log d$. In this article, we give a lower bound for $L(\phi )$ for maps $\phi$ defined over non-Archimedean fields $K$. The bound depends only on the degree $d$ and the Lipschitz constant of $\phi$. For maps $\phi$ whose Julia sets satisfy a certain boundedness condition, we are able to remove the dependence on the Lipschitz constant.References
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Additional Information
- Kenneth Jacobs
- Affiliation: Department of Mathematics, Northwestern University, Evanston, Illinois 60208
- MR Author ID: 1167375
- Email: kjacobs@math.northwestern.edu
- Received by editor(s): October 18, 2016
- Received by editor(s) in revised form: March 6, 2017, and May 10, 2017
- Published electronically: February 1, 2019
- Additional Notes: The author gratefully acknowledges support from NSF grant DMS-1344994 of the RTG in Algebra, Algebraic Geometry, and Number Theory, at the University of Georgia.
- © Copyright 2019 American Mathematical Society
- Journal: Trans. Amer. Math. Soc. 371 (2019), 6025-6046
- MSC (2010): Primary 37P50, 11S82; Secondary 37P05
- DOI: https://doi.org/10.1090/tran/7344
- MathSciNet review: 3937317