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Symbolic dynamics for the Teichmueller flow

Ursula Hamenstädt

TL;DR

This work develops a symbolic coding for the Teichmüller flow on any component $\mathcal{Q}$ of a stratum of quadratic or abelian differentials by combining train-track technology with a subshift of finite type. A finite-to-one semi-conjugacy from a suspension of a transitive shift to the Teichmüller flow is first established on a dense set, and then extended to a countable-alphabet system to control non-compactness and apply thermodynamic formalism. The paper proves that the $\Phi^t$-invariant Lebesgue measure on $\mathcal{Q}$ is the unique measure of maximal entropy, using Sarig’s theory for countable Markov shifts and prior entropy-maximization results, with implications for the dynamics near the principal boundary of strata. The methodology provides a robust framework for entropy analysis in moduli spaces and sets the stage for potential extensions to affine invariant manifolds and boundary behavior in subsequent work.

Abstract

Let Q be a component of a stratum of abelian or quadratic differentials on an oriented surface of genus $g\geq 0$ with $m\geq 0$ punctures and $3g-3+m\geq 2$. We construct a subshift of finite type $(Ω,σ)$ and a Borel suspension of $(Ω,σ)$ which admits a finite-to-one semi-conjugacy into the Teichmueller flow $Φ^t$ on Q. This is used to show that the $Φ^t$-invariant Lebesgue measure on Q is the unique measure of maximal entropy.

Symbolic dynamics for the Teichmueller flow

TL;DR

This work develops a symbolic coding for the Teichmüller flow on any component of a stratum of quadratic or abelian differentials by combining train-track technology with a subshift of finite type. A finite-to-one semi-conjugacy from a suspension of a transitive shift to the Teichmüller flow is first established on a dense set, and then extended to a countable-alphabet system to control non-compactness and apply thermodynamic formalism. The paper proves that the -invariant Lebesgue measure on is the unique measure of maximal entropy, using Sarig’s theory for countable Markov shifts and prior entropy-maximization results, with implications for the dynamics near the principal boundary of strata. The methodology provides a robust framework for entropy analysis in moduli spaces and sets the stage for potential extensions to affine invariant manifolds and boundary behavior in subsequent work.

Abstract

Let Q be a component of a stratum of abelian or quadratic differentials on an oriented surface of genus with punctures and . We construct a subshift of finite type and a Borel suspension of which admits a finite-to-one semi-conjugacy into the Teichmueller flow on Q. This is used to show that the -invariant Lebesgue measure on Q is the unique measure of maximal entropy.

Paper Structure

This paper contains 19 sections, 26 theorems, 74 equations, 1 figure.

Key Result

Theorem 1

Let ${\mathcal{Q}}$ be a component of a stratum of quadratic or abelian differentials. Then there exists and a finite-to-one semi-conjugacy $\Xi:(X,\Theta^t)\to ({\mathcal{Q}},\Phi^t)$ which maps the space of $\Theta^t$-invariant Borel probability measures on $X$ continuously onto ${\mathcal{M}}_{\rm inv}({\mathcal{Q}})$.

Figures (1)

  • Figure :

Theorems & Definitions (58)

  • Theorem 1
  • Theorem 2
  • Definition 2.1: Definition 2.1 of H22
  • Remark 2.2
  • Definition 2.3: Definition 2.8 of H22
  • Proposition 2.4: Proposition 3.2 and Proposition 3.3 of H22
  • Definition 3.1
  • Definition 3.2
  • Definition 3.3
  • Lemma 3.4
  • ...and 48 more