Real Polynomial Diffeomorphisms with Maximal Entropy: Tangencies

Nontransverse heterodimensional cycles: stabilisation and robust tangencies

We consider three-dimensional diffeomorphisms having simultaneously heterodimensional cycles and heterodimensional tangencies associated to saddle-foci. These cycles lead to a completely nondominated bifurcation setting. For every $r\geqslant 2$, we exhibit a class of such diffeomorphisms whose heterodimensional cycles can be $C^r$ stabilised and (simultaneously) approximated by diffeomorphisms with $C^r$ robust homoclinic tangencies. The complexity of our nondominated setting with plenty of homoclinic and heteroclinic intersections is used to overcome the difficulty of performing $C^r$ pertur…

Robust Heteroclinic Tangencies

We construct diffeomorphisms in dimension $d\geq 2$ exhibiting $C^1$-robust heteroclinic tangencies.

Linear response theory for diffeomorphisms with tangencies of stable and unstable manifolds. [A contribution to the Gallavotti-Cohen chaotic hypothesis.]

This note presents a non-rigorous study of the linear response for an SRB (or `natural physical') measure $ρ$ of a diffeomorphism $f$ in the presence of tangencies of the stable and unstable manifolds of $ρ$. We propose that generically, if $ρ$ has no zero Lyapunov exponent, if its stable dimension is sufficiently large (greater than 1/2 or perhaps 3/2) and if it is exponentially mixing in a suitable sense, then the following formal expression for the first derivative of $ρ(ϕ)$ with respect to $f$ along $X$ is convergent: $$ Ψ(z)=\sum_{n=0}^\infty z^n\intρ(dx)\,X(x)\cdot\nabla_x(ϕ\circ f^n)\qq…

On measure expansive diffeomorphisms

Let $f: M \to M$ be a diffeomorphism defined on a compact boundaryless $d$-dimensional manifold $M$, $d\geq 2$. C. Morales has proposed the notion of measure expansiveness. In this note we show that diffeomorphisms in a residual subset far from homoclinic tangencies are measure expansive. We also show that surface diffeomorphisms presenting homoclinic tangencies can be $C^1$-approximated by non-measure expansive diffeomorphisms.

Birth of discrete Lorenz attractors at the bifurcations of 3D maps with homoclinic tangencies to saddle points

It was established in 2006 that bifurcations of three-dimensional diffeomorphisms with a homoclinic tangency to a saddle-focus fixed point with the Jacobian equal to 1 can lead to Lorenz-like strange attractors. In the present paper we prove an analogous result for three-dimensional diffeomorphisms with a homoclinic tangency to a saddle fixed point with the Jacobian equal to 1, provided the quadratic homoclinic tangency under consideration is non-simple.

Heterodimensional tangencies on cycles leading to strange attractors

In this paper, we study heterodimensional cycles of two-parameter families of 3-dimensional diffeomorphisms some element of which contains nondegenerate heterodimensional tangencies of the stable and unstable manifolds of two saddle points with different indexes, and prove that such diffeomorphisms can be well approximated by another element which has a quadratic homoclinic tangency associated to one of these saddle points. Moreover, it is shown that the tangency unfolds generically with respect to the family. This result together with some theorem in Viana, we detect strange attractors appear…

通过Hopf分岔源自同宿切的异维环

Heterodimensional cycles derived from homoclinic tangencies via Hopf bifurcations

本研究分析满足$|λγ|=1$的三维$C^r$微分同胚的二次焦鞍同宿切，通过三参数开折证明其上存在Hopf分岔及分岔周期轨道的同宿点，得出原映射可被具余指标一异维环的微分同胚$C^r$逼近的结论。

Hyperbolicity and Quasi-hyperbolicity in Polynomial Diffeomorphisms of ${\Bbb C}^2$

We consider complex Henon maps which are quasi-hyperbolic. We show that a quasi-hyperbolic map is uniformly hyperbolic if and only if there are no tangencies between stable and unstable manifolds.

Moduli of 3-dimensional diffeomorphisms with saddle-foci

We consider a space $\mathcal{U}$ of 3-dimensional diffeomorphisms $f$ with hyperbolic fixed points $p$ the stable and unstable manifolds of which have quadratic tangencies and satisfying some open conditions and such that $Df(p)$ has non-real expanding eigenvalues and a real contracting eigenvalue. The aim of this paper is to study moduli of diffeomorphisms in $\mathcal{U}$. We show that, for a generic element $f$ of $\mathcal{U}$, all the eigenvalues of $Df(p)$ are moduli and the restriction of a conjugacy homeomorphism to a local unstable manifold is a uniquely determined linear conformal m…

二维复空间中的退化同宿分岔

Degenerate homoclinic bifurcations in complex dimension 2

研究二维复空间中同宿分岔，通过采用Takens论证证明展开非持久同宿相切的族含二次相切，结合相关成果得到复亨农映射分岔轨迹中鲁棒同宿相切丰富，还研究了由持久相切族引起的分岔，为复纽豪斯现象提供新途径。

C^r surface diffeomorphisms with no maximal entropy measure

For any $1\leq r<\infty$, we build on the disk and therefore on any manifold, a $C^r$-diffeomorphism with no measure of maximal entropy.

Maximal entropy measures of diffeomorphisms of circle fiber bundles

We characterize the maximal entropy measures of partially hyperbolic C^2 diffeomorphisms whose center foliations form circle bundles, by means of suitable finite sets of saddle points, that we call skeletons. In the special case of 3-dimensional nilmanifolds other than the torus, this entails the following dichotomy: either the diffeomorphism is a rotation extension of an Anosov diffeomorphism -- in which case there is a unique maximal measure, with full support and zero center Lyapunov exponents -- or there exist exactly two ergodic maximal measures, both hyperbolic and whose center Lyapunov …

Ledrappier-Young 熵公式在具有控制分解的 $C^1$ 微分同胚上的推广 第一部分：不稳定熵公式与不变性原理

Ledrappier-Young entropy formula for $C^1$ diffeomorphisms with dominated splitting Part 1: Unstable entropy formula and invariance principle

本文证明在零 Lyapunov 指数重数为 1 且具有控制分解的 $C^1$ 微分同胚中，中心方向不贡献熵，不稳定熵等于度量熵，将 Ledrappier-Young 公式推广到 $C^1$ 情形，并得到不变性原理及最大熵测度结果的应用。

Measures of maximal entropy for surface diffeomorphisms

We show that $C^\infty$ surface diffeomorphisms with positive topological entropy have at most finitely many ergodic measures of maximal entropy in general, and at most one in the topologically transitive case. This answers a question of Newhouse, who proved that such measures always exist. To do this we generalize Smale's spectral decomposition theorem to non-uniformly hyperbolic surface diffeomorphisms, we introduce homoclinic classes of measures, and we study their properties using codings by irreducible countable state Markov shifts.

On the number of ergodic measures of maximal entropy for partially hyperbolic diffeomorphisms with compact center leaves

In this paper, we study the number of ergodic measures of maximal entropy for partially hyperbolic diffeomorphisms defined on $3-$torus with compact center leaves. Assuming the existence of a periodic leaf with Morse-Smale dynamics we prove a sharp upper bound for the number of maximal measures in terms of the number of sources and sinks of Morse-Smale dynamics. A well-known class of examples for which our results apply are the so-called Kan-type diffeomorphisms admitting physical measures with intermingled basins.

Maximal measure and entropic continuity of Lyapunov exponents for $C^r$ surface diffeomorphisms with large entropy

We prove a finite smooth version of the entropic continuity of Lyapunov exponents of Buzzi-Crovisier-Sarig for $C^\infty$ surface diffeomorphisms [9]. As a consequence we show that any $C^r$, $r > 1$, smooth surface diffeomorphism $f$ with $h_{top}(f) > \frac{1}{r} \limsup_n \frac{1}{n} \log^+ \|df^n\|$ admits a measure of maximal entropy. We also prove the $C^r$ continuity of the topological entropy at $f$.

具有紧中心叶的拓扑传递部分双曲微分同胚的最大熵遍历测度的刻画

Characterization of Ergodic Measures of Maximal Entropy for Topologically Transitive Partially Hyperbolic Diffeomorphisms with compact center leaves

该文研究三维环面上具紧一维中心叶的拓扑传递部分双曲微分同胚，给出零Lyapunov指数的最大熵遍历测度的数量上界，并完整刻画其支撑集。

一个开集的部分双曲微分同胚的有限个最大熵测度

Finite Measures of Maximal Entropy for an Open Set of Partially Hyperbolic Diffeomorphisms

本文研究一维中心方向且不稳定熵大于稳定熵的部分双曲微分同胚，证明其仅有有限个遍历最大熵测度，并将相关结果推广至任意维度。

Global and local bifurcations, three-dimensional Henon maps and discrete Lorenz attractors

Lorenz attractors play an important role in the modern theory of dynamical systems. The reason is that they are robust, i.e. preserve their chaotic properties under various kinds of perturbations. This means that such attractors can exist in applied models and be observed in experiments. It is known that discrete Lorenz attractors can appear in local and global bifurcations of multidimensional diffeomorphisms. However, to date, only partial cases were investigated. In this paper bifurcations of homoclinic and heteroclinic cycles with quadratic tangencies of invariant manifolds are studied. A f…

具有有限个最大熵测度的部分双曲微分同胚

Partially hyperbolic diffeomorphisims with a finite number of measures of maximal entropy

本文证明在中心方向具有一维支配分解且李雅普诺夫指数一致有界的部分双曲微分同胚，其最大熵遍历测度有限，并应用于Anosov派生类及斜积类，同时研究测度数目的上半连续性。

Constant periodic data and entropy of Anosov diffeomorphisms

We study the effects that the constant periodic data condition have on topological entropy of Anosov diffeomorphisms. Under constant periodic data condition we prove that Anosov diffeomorphism has finitely many measures of maximal entropy and each one of them is absolutely continuous with respect to Lebesgue. From this, in the setting of $C^{\infty}-$Anosov diffeomorphisms satisfying constant periodic data, we provide a characterization of transitivity property via measures of maximal entropy.

膨胀叶状结构的极大横截测度

Maximal transverse measures of expanding foliations

本研究针对微分同胚的膨胀叶状结构，通过动力学平均构造极大横截测度，证明其对一类微分同胚呈指数收敛且极限测度有有限遍历分解，揭示了该测度与极大u-熵测度的关联。

Polynomial diffeomorphisms of C^2, IV: The measure of maximal entropy and laminar currents

This paper concerns the dynamics of polynomial automorphisms of ${\bf C}^2$. One can associate to such an automorphism two currents $μ^\pm$ and the equilibrium measure $μ=μ^+\wedgeμ^-$. In this paper we study some geometric and dynamical properties of these objects. First, we characterize $μ$ as the unique measure of maximal entropy. Then we show that the measure $μ$ has a local product structure and that the currents $μ^\pm$ have a laminar structure. This allows us to deduce information about periodic points and heteroclinic intersections. For example, we prove that the support of $μ$ coincid…

$C^r$表面微分同胚最大熵遍历测度的连续性性质

Continuity properties of ergodic measures of maximal entropy for $C^r$ surface diffeomorphisms

本文研究了$C^r$表面微分同胚最大熵遍历测度的连续性性质，证明了其数量在特定条件下上半连续，并揭示了局部常数性的条件及极限点的遍历性。

Nonhyperbolicity of invariant measures on maximal attractor

The article states that for every compact manifold M of dimension 4 or higher there is an area U in a set of smooth diffeomorphisms over M such that every map f from U has local maximal partially hyperbolic attractor and nonatomic ergodic invariant measure on it where one of Lyapunov exponents vanish. The result is first proved for skew products over horseshoe and then transferred onto smooth diffeomorphisms.

A relation between entropy and transitivity of Anosov diffeomorphisms

It is known that transitive Anosov diffeomorphisms have a unique measure of maximal entropy (MME). Here we discuss the converse question. Under suitable hypothesis on Lyapunov exponents on the set of periodic points and the structure of the MME we get transitivity of $C^1-$Anosov diffeomorphisms.

Real Polynomial Diffeomorphisms with Maximal Entropy: II. Small Jacobian

This paper concerns the Henon family of diffeomorphisms of the plane for which the absolute value of the jacobian parameter is bounded by .08. We describe the parameter locus for which the mapping is a horseshoe.

A dichotomy for measures of maximal entropy near time-one maps of transitive Anosov flows

We show that time-one maps of transitive Anosov flows of compact manifolds are accumulated by diffeomorphisms robustly satisfying the following dichotomy: either all of the measures of maximal entropy are non-hyperbolic, or there are exactly two ergodic measures of maximal entropy, one with a positive central exponent and the other with a negative central exponent. We establish this dichotomy for certain partially hyperbolic diffeomorphisms isotopic to the identity whenever both of their strong foliations are minimal. Our proof builds on the approach developed by Margulis for Anosov flows wher…

Area preserving surface diffeomorphisms with polynomial decay of correlations are ubiquitous

We show that any surface admits an area preserving $C^{1+β}$ diffeomorphism with non-zero Lyapunov exponents which is Bernoulli and has polynomial decay of correlations. We establish both upper and lower polynomial bounds on correlations. In addition, we show that this diffeomorphism satisfies the Central Limit Theorem and has the Large Deviation Property. Finally, we show that the diffeomorphism we constructed possesses a unique hyperbolic Bernoulli measure of maximal entropy with respect to which it has exponential decay of correlations.

具有SRB性质的最大熵测度

Measures of maximal entropy that are SRB

本文研究$T^3$上DA-微分同胚的最大熵测度的SRB性质，给出其为SRB测度的充要条件（正Lyapunov指数和在支撑集周期轨道上与线性Anosov映射一致），并指出该刚性结果弱于Katok猜想且附示例。

Maximal pseudometrics and distortion of circle diffeomorphisms

We initiate a study of distortion elements in the Polish groups $\mbox{Diff}_+^k(\mathbb{S}^1)$ ($1\leq k<\infty$), as well as $\mbox{Diff}_+^{1+AC}(\mathbb{S}^1)$, in terms of maximal metrics on these groups. We classify distortion in the $k=1$ case: a $C^1$ circle diffeomorphism is $C^1$-undistorted if and only if it has a hyperbolic periodic point. On the other hand, answering a question of Navas, we exhibit analytic circle diffeomorphisms with only non-hyperbolic fixed points which are $C^{1+AC}$-undistorted, and hence $C^k$-undistorted for all $k\geq 2$. In the appendix, we exhibit a maxi…

$C^\infty$ 三维流的最大熵测度

Measures of maximal entropy for $C^\infty$ three-dimensional flows

本文证明无边界紧致三维流形上具有正熵的 $C^\infty$ 非奇异流至多存在有限个遍历最大熵测度，推广了 Buzzi-Crovisier-Sarig 的结果，并通过处理 Lyapunov 指数连续性和 Pesin 集均匀大性给出了新证明。

某些与Anosov同伦的映射的极大熵测度的双曲性

Hyperbolicity of maximal entropy measures for certain maps isotopic to Anosov

证明了具有紧致二维中心叶理的环面部分双曲系统遍历极大熵测度的双曲性。

Volume growth and entropy for $C^1$ partially hyperbolic diffeomorphisms

We show that the metric entropy of a $C^1$ diffeomorphism with a dominated splitting and the dominating bundle uniformly expanding is bounded from above by the integrated volume growth of the dominating (expanding) bundle plus the maximal Lyapunov exponent from the dominated bundle multiplied by its dimension. We also discuss different types of volume growth that can be associated with an expanding foliation and relationships between them, specially when there exists a closed form non-degenerate on the foliation. Some consequences for partially hyperbolic diffeomorphisms are presented.

$\mathcal{C}^2$ 曲面微分同胚中具有大 Lyapunov 指数的测度同宿类的有限性

Finitness of measured homoclinic classes with large Lyapunov exponents for $\mathcal{C}^2$ surface diffeomorphisms

本文证明了 $\mathcal{C}^2$ 曲面微分同胚中具有大 Lyapunov 指数的测度同宿类的有限性，并由此导出系统熵较大时最大熵遍历测度集合的有限性。

Existence and uniqueness of maximizing measures for robust classes of local diffeomorphisms

We prove existence of maximal entropy measures for an open set of non-uniformly expanding local diffeomorphisms on a compact Riemannian manifold. In this context the topological entropy coincides with the logarithm of the degree, and these maximizing measures are eigenmeasures of the transfer operator. When the map is topologically mixing, the maximizing measure is unique and positive on every open set.

Real-analytic diffeomorphisms with homogeneous spectrum and disjointness of convolutions

On any torus $\mathbb{T}^d$, $d \geq 2$, we prove the existence of a real-analytic diffeomorphism $T$ with a good approximation of type $\left(h,h+1\right)$, a maximal spectral type disjoint with its convolutions and a homogeneous spectrum of multiplicity two for the Cartesian square $T\times T$. The proof is based on a real-analytic version of the Approximation by Conjugation-method.

3-维 тор斯上 Anosov 流形的不稳定熵

Unstable entropy for Anosov diffeomorphisms on the 3-torus

本文研究了 3-维 торus 上 Anosov 流形的不稳定熵，通过构造 Margulis 测度系统，揭示了最大不稳定熵测度与共振态之间的关系。

Decay of correlations for maximal measure of maps derived from Anosov

It was proven by Ures that $C^1$ diffeomorphism on three dimensional torus that is derived from Anosov admits a unique maximal measure. Here we show that the maximal measure has exponential decay of correlations for Hölder observables, assuming the middle eigenvalue of the linear Anosov model is contracting.

Entropy rigidity and flexibility for suspension flows over Anosov diffeomorphisms

For any $C^\infty$, area-preserving Anosov diffeomorphism $f$ of a surface, we show that a suspension flow over $f$ is $C^\infty$-conjugate to a constant-time suspension flow of a hyperbolic automorphism of the two torus if and only if the volume measure is the measure with maximal entropy. We also show that the the metric entropy with respect to the volume measure and the topological entropy of suspension flow over Anosov diffeomorphisms on torus achieve all possible values. Our results fit into two programs related to entropy rigidity and flexibility of Anosov systems.

微分同胚的强正递归性与指数混合

Strong positive recurrence and exponential mixing for diffeomorphisms

本研究引入闭流形上微分同胚的强正递归（SPR）性质，证明其可通过具谱隙的可数状态马尔可夫移位编码，推导最大熵测度的多种遍历性质，验证正熵C∞曲面微分同胚及更多低正则、高维情形满足SPR。

Thermodynamical $u$-formalism I: measures of maximal $u$-entropy for maps that factor over Anosov

We construct measures of maximal $u$-entropy for any partially hyperbolic diffeomorphism that factors over an Anosov torus automorphism and has mostly contracting center direction. The space of such measures has a finite dimension, and its extreme points are ergodic measures with pairwise disjoint supports.

Homoclinic tangency and variation of entropy

In this paper we study the effect of a homoclinic tangency in the variation of the topological entropy. We prove that a diffeomorphism with a homoclinic tangency associated to a basic hyperbolic set with maximal entropy is a point of entropy variation in the $C^{\infty}$-topology. We also prove results about variation of entropy in other topologies and when the tangency does not correspond to a basic set with maximal entropy. We also show an example of discontinuity of the entropy among $C^{\infty}$ diffeomorphisms of three dimensional manifolds.

Intrinsic ergodicity for certain nonhyperbolic robustly transitive systems

We show that a class of robustly transitive diffeomorphisms originally described by Mañé are intrinsically ergodic. More precisely we obtain an open set of diffeomorphisms which fail to be uniformly hyperbolic, but nevertheless have constant entropy and isomorphic unique measures of maximal entropy.

Distribution of periodic points of polynomial diffeomorphisms of C^2

This paper deals with the dynamics of a simple family of holomorphic diffeomorphisms of $\C^2$: the polynomial automorphisms. This family of maps has been studied by a number of authors. We refer to [BLS] for a general introduction to this class of dynamical systems. An interesting object from the point of view of potential theory is the equilibrium measure $μ$ of the set $K$ of points with bounded orbits. In [BLS] $μ$ is also characterized dynamically as the unique measure of maximal entropy. Thus $μ$ is also an equilibrium measure from the point of view of the thermodynamical formalism. In t…

Properties of the maximal entropy measure and geometry of Hénon attractors

We consider an abundant class of non-uniformly hyperbolic $C^2$-Hénon like diffeomorphisms called strongly regular and which corresponds to Benedicks-Carleson parameters. We prove the existence of $m>0$ such that for any such diffeomorphism $f$, every invariant probability measure of $f$ has a Lyapunov exponent greater than $m$, answering a question of L. Carleson. Moreover, we show the existence and uniqueness of a measure of maximal entropy, this answers a question of M. Lyubich and Y. Pesin. We also prove that the maximal entropy measure is equi-distributed on the periodic points and is fin…

非可达拓扑斜积的极大熵测度

Maximal Entropy Measures for Non-Accessible Topological Skew Products

本文研究一维紧致中心叶层的部分双曲微分同胚，证明在流形为不稳定叶状结构饱和的唯一极小不变集时，极大熵测度要么唯一且非双曲，要么恰有两个双曲遍历测度。

光滑曲面微分同胚的Lyapunov指数与熵的不连续性

Discontinuity of Lyapunov exponents vs Entropy for smooth surface diffeomorphisms

研究光滑曲面微分同胚中Lyapunov指数与熵的关系，通过简化论证展示最大熵测度附近指数的连续性性质。

$\boldsymbol{\frak{C}}^{1,\boldsymbol{\frak{\u03b1}}}$微分同胚的度量熵的上半连续性

Upper semi-continuity of metric entropy for $\mathcal{C}^{1,α}$ diffeomorphisms

针对三维$\boldsymbol{\frak{C}}^{1,\boldsymbol{\frak{\u03b1}}}$微分同胚，通过均匀分划建立度量熵的均匀逼近，得到熵映射上半连续性、强正回归条件改进及最大熵测度维数连续性等结论。

The almost Borel structure of surface diffeomorphisms, Markov shifts and their factors

Extending work of Hochman, we study the almost-Borel structure, i.e., the nonatomic invariant probability measures, of symbolic systems and surface diffeomorphisms. We first classify Markov shifts and characterize them as strictly universal with respect to a natural family of classes of Borel systems. We then study their continuous factors showing that a low entropy part is almost-Borel isomorphic to a Markov shift but that the remaining part is much more diverse, even for finite-to-one factors. However, we exhibit a new condition which we call "Bowen type" which gives complete control of thos…

The almost Borel structure of diffeomorphisms with some hyperbolicity

These lecture notes focus on a recent result of Mike Hochman: an arbitrary standard Borel system can be embedded into a mixing Markov with equal entropy, respecting all invariant probability measures, with two exceptions: those carried by periodic orbits and those with maximal entropy. We discuss the corresponding notions of almost Borel embedding and isomorphism and universality. The main part of this paper is devoted to a self-contained and detailed proof of Hochman's theorem. We then explain how Katok's horseshoe theorem can be used to analyze diffeomorphisms with "enough" measures that are…

光滑鞍形曲面自同态的最大熵测度的有限性

Finiteness of measures of maximal entropy for smooth saddle surface endomorphisms

本文针对拓扑熵大于度的对数的闭曲面$\mathcal{C}^{\infty}$局部微分同胚，通过构造具马尔可夫性的几何矩形族、结合Yomdin理论分析不稳定曲线迭代行为，证明这类映射的最大熵遍历测度数目有限。

Center Specification Property and Entropy for Partially Hyperbolic Diffeomorphisms

Let $f$ be a partially hyperbolic diffeomorphism on a closed (i.e., compact and boundaryless) Riemannian manifold $M$ with a uniformly compact center foliation $\mathcal{W}^{c}$. The relationship among topological entropy $h(f)$, entropy of the restriction of $f$ on the center foliation $h(f, \mathcal{W}^{c})$ and the growth rate of periodic center leaves $p^{c}(f)$ is investigated. It is first shown that if a compact locally maximal invariant center set $Λ$ is center topologically mixing then $f|_Λ$ has the center specification property, i.e., any specification with a large spacing can be cen…

u-吉布斯测度的熵刚性

Rigidity for $u$-Gibbs measures admitting Margulis systems

本文研究了u-吉布斯测度的熵刚性，证明在特定条件下雅可比数据为常数，并探讨了其在不同映射类型中的应用与结论。