Anosov automorphisms on nilmanifolds in dimensions 9 and 10
Meera G. Mainkar, Cynthia E. Will
备注:
A new paper "Characterization of of 9-dimensional Anosov Lie algebras", arXiv:1411.2006, was submitted which contains stronger results than this version. Work on 10-dimensional Anosov Lie algebras is in progress
We study 9 and 10-dimensional Anosov Lie algebras, by using the properties of very special algebraic numbers. We classify k-step complex Anosov Lie algebras for $k>2$ and in the two step case, we give an example in each possible type, or we give a non-existence result.
Anosov diffeomorphisms on closed Riemannian manifolds are a type of dynamical systems exhibiting uniform hyperbolic behavior. Therefore their properties are intensively studied, including which spaces allow such a diffeomorphism. It is conjectured that any closed manifold admitting an Anosov diffeomorphism is homeomorphic to an infra-nilmanifold, i.e. a compact quotient of a 1-connected nilpotent Lie group by a discrete group of isometries. This conjecture motivates the problem of describing which infra-nilmanifolds admit an Anosov diffeomorphism. So far, most research was focused on the restr…
A few years ago, the first example of a closed manifold admitting an Anosov diffeomorphism but no expanding map was given. Unfortunately, this example is not explicit and is high-dimensional, although its exact dimension is unknown due to the type of construction. In this paper, we present a family of concrete 12-dimensional nilmanifolds with an Anosov diffeomorphism but no expanding map, where nilmanifolds are defined as the quotient of a 1-connected nilpotent Lie group by a cocompact lattice. We show that this family has the smallest possible dimension in the class of infra-nilmanifolds, whi…
Let $S=\{p_1, \dots, p_r,\infty\}$ for prime integers $p_1, \dots, p_r.$ Let $X$ be an $S$-adic compact nilmanifold, equipped with the unique translation invariant probability measure $μ.$ We characterize the countable groups $Γ$ of automorphisms of $X$ for which the Koopman representation $κ$ on $L^2(X,μ)$ has a spectral gap. More specifically, we show that $κ$ does not have a spectral gap if and only if there exists a non-trivial $Γ$-invariant quotient solenoid (that is, a finite-dimensional, connected, compact abelian group) on which $Γ$ acts as a virtually abelian group.
Bootstrap for local rigidity of Anosov automorphisms on the 3-torus
建立了具有实谱的3-环面的双曲自同构的强局部刚性形式。即,设$L\colon\mathbb T^3\to\mathbb T^3$是具有实谱的3-环面的双曲自同构,$f$是$L$的$C^1$小扰动。则$f$光滑地($C^\infty$)共轭到$L$当且仅当由$f$的周期点处的特征值给出的对$C^1$共轭性的障碍消失。通过结合我们的结果和局部刚性结果的Kalinin和Sadovskaya共形自同构,这完成了局部刚性程序的双曲自同构在3维。我们的工作推广了de la Llave-Marco-Moriyón的二维局部刚性理论。
For every irreducible automorphism $ϕ\in\text{SL}_3({\mathbb Z})$ of the $3$-torus, for which the product of the expanding eigenvalues is positive, we construct a pseudo-Anosov mapping $f$ of an associated surface, semi-conjugate and almost-isomorphic to $ϕ$, whose stretch factor is the product of the expanding eigenvalues of $ϕ$. This shows that any norm-$1$ cubic Pisot number occurs as the stretch factor of a pseudo-Anosov mapping, proving a conjecture of Fried in degree $3$. A similar construction works for the $4$-torus on condition that $ϕ$ has exactly two eigenvalues outside the unit cir…
In the present work we obtain rigidity results analysing the set of regular points, in the sense of Oseledec's Theorem. It is presented a study on the possibility of an Anosov diffeomorphisms having all Lyapunov exponents defined everywhere. We prove that this condition implies local rigidity of an Anosov automorphism of the torus $\mathbb{T}^d, d \geq 3,$ $C^1-$close to a linear automorphism diagonalizable over $\mathbb{R}$ and such that its characteristic polynomial is irreducible over $\mathbb{Q}.$
Consider actions of $\Z ^r$ by ergodic automorphisms on a compact nilmanifolds for $r \geq 2$. We show that small $C^k$ perturbations of such higher rank partially hyperbolic actions are smoothly conjugate to the original action, using a KAM scheme. The driving force for convergence of this iteration is the exponential mixing of the original action.