Geometric characterization of Lyapunov exponents for Riemann surface laminations
Viet-Anh Nguyen
备注:
Dedicated to the memory of Gennadi M. Henkin. To appear in the Henkin volume of the Journal of Geometric Analysis. In this fourth version, the exposition has been thoroughly improved
We characterize geometrically the Lyapunov exponents of a cocycle (of arbitrary rank) with respect to a harmonic current defined on a hyperbolic Riemann surface lamination. Our characterizations are formulated in terms of the expansion rates of the cocycle along geodesic rays.
Horocycle flows for laminations by hyperbolic Riemann surfaces and Hedlund's theorem
研究了紧致极小层$(M,\mathcal F)$的单位切丛$(\hat M, T^1\mathcal{F})$的测地线流和时圈流在负曲面上的动力学性质。我们给出的条件下,这些流的联合行动所产生的仿射群的行动是最小的,并在此行动是不是最小的例子。在第一种情况下,我们证明了如果$\mathcal F$有一个非单连通的叶,那么该单胞流是拓扑传递的。
This report discusses recent results as well as new perspectives in the ergodic theory for Riemann surface laminations, with an emphasis on singular holomorphic foliations by curves. The central notions of these developments are leafwise Poincaré metric, directed positive harmonic currents, multiplicative cocycles and Lyapunov exponents. We deal with various ergodic theorems for such laminations: Random and Operator Ergodic Theorems, (Geometric) Birkhoff Ergodic Theorems, Oseledec Multiplicative Ergodic Theorem and Unique Ergodicity Theorems. Applications of these theorems are also given. In p…
We study Lyapunov exponents for flat bundles over hyperbolic curves defined via parallel transport over the geodesic flow. We consider them as invariants on the space of Hitchin representations and show that there is a gap between any two consecutive Lyapunov exponents. Moreover we characterize the uniformizing representation of the Riemann surface as the one with the extremal gaps. The strategy of the proof is to relate Lyapunov exponents in the case of Anosov representations to other invariants, where the gap result is already available or where we can directly show it. In particular, firstl…
Let \Fc be a holomorphic foliation by Riemann surfaces defined on a compact complex projective surface X satisfying the following two conditions: (1) the singular points of \Fc are all hyperbolic; (2) \Fc is Brody hyperbolic. Then we establish cohomological formulas for the Lyapunov exponent and the Poincaré mass of an extremal positive \ddc-closed current tangent to \Fc. If, moreover, there is no nonzero positive closed current tangent to \Fc, then we show that the Lyapunov exponent χ(\Fc) of \Fc, which is, by definition, the Lyapunov exponent of the unique normalized positive \ddc-closed cur…
We investigate i.i.d. random complex dynamical systems generated by probability measures on finite unions of the loci of holomorphic families of rational maps on the Riemann sphere. We show that under certain conditions on the families, for a generic system, (especially, for a generic random polynomial dynamical system,) for all but countably many initial values $z$ in the Riemann sphere, for almost every sequence of maps $γ=(γ_{1},γ_{2},\ldots )$, the Lyapunov exponent of $γ$ at $z$ is negative. Also, we show that for a generic system, for every initial value $z$ in the Riemann sphere, the or…