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Transactions of the American Mathematical Society

Published by the American Mathematical Society since 1900, Transactions of the American Mathematical Society is devoted to longer research articles in all areas of pure and applied mathematics.

ISSN 1088-6850 (online) ISSN 0002-9947 (print)

The 2020 MCQ for Transactions of the American Mathematical Society is 1.48.

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Expansive Subdynamics
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by Mike Boyle and Douglas Lind PDF
Trans. Amer. Math. Soc. 349 (1997), 55-102 Request permission

Abstract:

This paper provides a framework for studying the dynamics of commuting homeomorphisms. Let $\alpha$ be a continuous action of $\mathbb {Z}^d$ on an infinite compact metric space. For each subspace $V$ of $\mathbb {R}^d$ we introduce a notion of expansiveness for $\alpha$ along $V$, and show that there are nonexpansive subspaces in every dimension $\le d-1$. For each $k\le d$ the set $\mathbb {E}_k(\alpha )$ of expansive $k$-dimensional subspaces is open in the Grassmann manifold of all $k$-dimensional subspaces of $\mathbb {R}^d$. Various dynamical properties of $\alpha$ are constant, or vary nicely, within a connected component of $\mathbb {E}_k(\alpha )$, but change abruptly when passing from one expansive component to another. We give several examples of this sort of “phase transition,” including the topological and measure-theoretic directional entropies studied by Milnor, zeta functions, and dimension groups. For $d=2$ we show that, except for one unresolved case, every open set of directions whose complement is nonempty can arise as an $\mathbb {E}_1(\alpha )$. The unresolved case is that of the complement of a single irrational direction. Algebraic examples using commuting automorphisms of compact abelian groups are an important source of phenomena, and we study several instances in detail. We conclude with a set of problems and research directions suggested by our analysis.
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Additional Information
  • Mike Boyle
  • Affiliation: Department of Mathematics, University of Maryland, College Park, Maryland 20742
  • MR Author ID: 207061
  • ORCID: 0000-0003-0050-0542
  • Email: mmb@math.umd.edu
  • Douglas Lind
  • Affiliation: Department of Mathematics, University of Washington, Box 354350, Seattle, Washington 98195–4350
  • MR Author ID: 114205
  • Email: lind@math.washington.edu
  • Received by editor(s): May 6, 1994
  • Additional Notes: The first author was supported in part by NSF Grants DMS-8802593, DMS-9104134, and DMS-9401538.
    The second author was supported in part by NSF Grants DMS-9004253 and DMS-9303240.
  • © Copyright 1997 American Mathematical Society
  • Journal: Trans. Amer. Math. Soc. 349 (1997), 55-102
  • MSC (1991): Primary 54H20, 58F03; Secondary 28D20, 28D15, 28F15, 58F11, 58F08
  • DOI: https://doi.org/10.1090/S0002-9947-97-01634-6
  • MathSciNet review: 1355295