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Documents  Pollicott, Mark | enregistrements trouvés : 13

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Outreach;Mathematics Education and Popularization of Mathematics

Mark Pollicott (born 24 September 1959) is a British mathematician known for his contributions to ergodic theory and dynamical systems. He has a particular interest in applications to other areas of mathematics, including geometry, number theory and analysis.

Pollicott attended High Pavement College in Nottingham, where his teachers included the Booker prize winning author Stanley Middleton. He gained a BSc in Mathematics and Physics in 1981 and a PhD in Mathematics in 1984 both at the University of Warwick. His PhD supervisor was Bill Parry and his thesis title The Ruelle Operator, Zeta Functions and the Asymptotic Distribution of Closed Orbits.

He held permanent positions at the University of Edinburgh, University of Porto, and University of Warwick before appointment to the Fielden Chair of Pure Mathematics in Manchester (1996-2004). He then returned to a professorship at Warwick in 2005. In addition, he has held numerous visiting positions including ones at the IHES in Paris, the Institute for Advanced Study in Princeton, MSRI in University of California, Berkeley, Caltech and Grenoble. He has been recipient of a Royal Society University Research Fellowship, two Leverhulme Trust Senior Research Fellowships and an E.U. Marie Curie Chair.
Mark Pollicott (born 24 September 1959) is a British mathematician known for his contributions to ergodic theory and dynamical systems. He has a particular interest in applications to other areas of mathematics, including geometry, number theory and analysis.

Pollicott attended High Pavement College in Nottingham, where his teachers included the Booker prize winning author Stanley Middleton. He gained a BSc in Mathematics and Physics in 1981 ...

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- 484 p.
ISBN 978-0-521-57688-8

London mathematical society lecture note series , 0228

Localisation : Collection 1er étage

Zelta action # Zeta d action # Zeta réaction # automorphisme de groupe compact # dimension de Hausdorff # flux sur espace homogène # invariant K-théorique # principe variationnel # propriété de rigidité # système dynamique # théorie de Ramsey # théorie des nombres combinatoire # théorie ergodique

05C55 ; 22D40 ; 28Dxx ; 47A35 ; 54H20

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Research talks;Dynamical Systems and Ordinary Differential Equations;Geometry;Number Theory

Given the Apollonian Circle packing, or something similar, one can consider the distribution of the logarithms of the radii. These can be shown to satisfy a Central Limit Theorem. The method of proof uses iterated function schemes and transfer operators and has applications to other conformal dynamical systems.

52C26 ; 37C30 ; 11K55 ; 37F35 ; 37D35

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Research schools

When a dynamical system admitting a natural (SRB) measure is perturbed, it is natural to ask how the SRB measure responds to the perturbation. In the tamest cases, this response is linear, and the derivative of the SRB measure with respect to the parameter can be expressed as a sum of decorrelations (involving the derivative of the system with respect to the parameter). In more subtle situations - for example, systems with bifurcations, or observables with singularities - the SRB measure may be a Hölder function of the parameter. This talk will present a panorama of results about linear and fractional response. When a dynamical system admitting a natural (SRB) measure is perturbed, it is natural to ask how the SRB measure responds to the perturbation. In the tamest cases, this response is linear, and the derivative of the SRB measure with respect to the parameter can be expressed as a sum of decorrelations (involving the derivative of the system with respect to the parameter). In more subtle situations - for example, systems with bifurcations, or ...

37D20

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Works by Sarig and Benovadia have built symbolic dynamics for arbitrary diffeomorphisms of compact manifolds. This shows thatthere can be at most countably many ergodic hyperbolic equilibriummeasures for any Holder continuous or geometric potentials. We will explain how this yields uniqueness inside each homoclinic class of measures, i.e., of ergodic and hyperbolic measures that are homoclinically related. In some cases, further topological or geometric arguments can show global uniqueness.
This is a joint work with Sylvain Crovisier and Omri Sarig
Works by Sarig and Benovadia have built symbolic dynamics for arbitrary diffeomorphisms of compact manifolds. This shows thatthere can be at most countably many ergodic hyperbolic equilibriummeasures for any Holder continuous or geometric potentials. We will explain how this yields uniqueness inside each homoclinic class of measures, i.e., of ergodic and hyperbolic measures that are homoclinically related. In some cases, further topological or ...

37C40

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Research schools

$Let (X,T)$ be a dynamical system preserving a probability measure $\mu $. A concentration inequality quantifies how small is the probability for $F(x,Tx,\ldots,T^{n-1}x)$ to deviate from $\int F(x,Tx,\ldots,T^{n-1}x) \mathrm{d}\mu(x)$ by an given amount $u$, where $F:X^n\to\mathbb{R}$ is supposed to be separately Lipschitz. The bound on that probability involves a constant $C$ depending only on the dynamical system (thus independent of $n$), and $\sum_{i=0}^{n-1} \mathrm{Lip}_i(F)^2$. In the best situation, the bound is $\exp(-C u^2/\sum_{i=0}^{n-1} \mathrm{Lip}_i(F)^2)$.
After explaining how to get such a bound for independent random variables, I will show how to prove it for a Gibbs measure on a shift of finite type with a Lipschitz potential, and present examples of functions $F$ to which one can apply the inequality. Finally, I will survey some results obtained for nonuniformly hyperbolic systems modeled by Young towers.
$Let (X,T)$ be a dynamical system preserving a probability measure $\mu $. A concentration inequality quantifies how small is the probability for $F(x,Tx,\ldots,T^{n-1}x)$ to deviate from $\int F(x,Tx,\ldots,T^{n-1}x) \mathrm{d}\mu(x)$ by an given amount $u$, where $F:X^n\to\mathbb{R}$ is supposed to be separately Lipschitz. The bound on that probability involves a constant $C$ depending only on the dynamical system (thus independent of $n$), ...

37D20 ; 37D25 ; 37A50

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Research schools

We study dynamics of geodesic flows over closed surfaces of genus greater than or equal to 2 without focal points. Especially, we prove that there is a large class of potentials having unique equilibrium states, including scalar multiples of the geometric potential, provided the scalar is less than 1. Moreover, we discuss ergodic properties of these unique equilibrium states. We show these unique equilibrium states are Bernoulli, and weighted regular periodic orbits are equidistributed relative to these unique equilibrium states. We study dynamics of geodesic flows over closed surfaces of genus greater than or equal to 2 without focal points. Especially, we prove that there is a large class of potentials having unique equilibrium states, including scalar multiples of the geometric potential, provided the scalar is less than 1. Moreover, we discuss ergodic properties of these unique equilibrium states. We show these unique equilibrium states are Bernoulli, and weighted ...

37D35 ; 37D40 ; 37D25

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For a wide range of values of the incoming solar radiation, the Earth features at least two attracting states, which correspond to competing climates. The warm climate is analogous to the present one, the snowball climate features global glaciation and conditions that can hardly support life forms. Paleoclimatic evidences suggest that in past our planet flipped between these two states. The main physical mechanism responsible for such instability is the ice-albedo feedback. In a previous work, we defined the Melancholia states that sit between the two climates. Such states are embedded in the boundaries between the two basins of attraction and feature extensive glaciation down to relatively low latitudes. Here, we explore the global stability properties of the system by introducing random perturbations as modulations to the intensity of the incoming solar radiation. We observe noise-induced transitions between the competing basins of attractions. In the weak noise limit, large deviation laws define the invariant measure and the statistics of escape times. By empirically constructing the instantons, we show that the Melancholia states are the gateways for the noise-induced transitions. In the region of multistability, in the zero-noise limit, the measure is supported only on one of the competing attractors. For low (high) values of the solar irradiance, the limit measure is the snowball (warm) climate. The changeover between the two regimes corresponds to a first order phase transition in the system. The framework we propose seems of general relevance for the study of complex multistable systems. At this regard, we relate our results to the debate around the prominence of contigency vs. convergence in biological evolution. Finally, we propose a new method for constructing Melancholia states from direct numerical simulations, thus bypassing the need to use the edge-tracking algorithm. For a wide range of values of the incoming solar radiation, the Earth features at least two attracting states, which correspond to competing climates. The warm climate is analogous to the present one, the snowball climate features global glaciation and conditions that can hardly support life forms. Paleoclimatic evidences suggest that in past our planet flipped between these two states. The main physical mechanism responsible for such i...

82C26 ; 60Gxx ; 37D45 ; 85A20 ; 76E20

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Research schools

In this talk, we will discuss various growth rates associated to Anosov flows and their covers. The topological entropy of an Anosov flow on a compact manifold is realised as the exponential growth rate of its periodic orbits. If we pass to a regular cover of the manifold then we can consider a corresponding growth rate for the lifted flow. This growth is bounded above by the topological entropy but if the cover is infinite then the growth rate may be strictly smaller. For abelian covers, this phenomenon admits a precise description in terms of a variational principle. More recent work, joint with Rhiannon Dougall, considers more general infinite covers. In this talk, we will discuss various growth rates associated to Anosov flows and their covers. The topological entropy of an Anosov flow on a compact manifold is realised as the exponential growth rate of its periodic orbits. If we pass to a regular cover of the manifold then we can consider a corresponding growth rate for the lifted flow. This growth is bounded above by the topological entropy but if the cover is infinite then the growth rate ...

37D20 ; 37D35 ; 37D40 ; 37B40

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I will present some joint works with Volker Mayer in which we primarily show that for a large class of entire and meromorphic transcendental functions the full geometric thermodynamic formalism holds. Most notably, this means that the transfer operators generated by geometric potentials are well dened and bounded after an appropriate conformal change of Riemannian metric on the complex plane C. We show that these operators are quasi-compact of diagonal type with one leading eigenvalue, which in addition is simple. In particular, the dual operators have positive eigenvalues and eigenvectors that are Borel probability eigenmeasures. The probability measure obtained by integrating these eigenmeasures against leading eigenfanctions of transfer operators are invariant. We show that these measures are equilibrium states of geometric potentials. The primary applications of these theorems capture the stochastic laws such as exponential decay of correlations, the central limit theorem, and the law of iterated logarithm. it also permits us to provide exact formulas (of Bowen’s type) for Hausdorff dimension of radial Julia sets and multifractal analysis. We will discuss two distinct routes (leading to different though overlapping classes of meromorphic transcendental functions) to get the geometric thermodynamic formalism. One of them is based on Nevanlina’s theory and the other on analogues of integral means spectrum from classical complex analysis of conformal maps. I will present some joint works with Volker Mayer in which we primarily show that for a large class of entire and meromorphic transcendental functions the full geometric thermodynamic formalism holds. Most notably, this means that the transfer operators generated by geometric potentials are well dened and bounded after an appropriate conformal change of Riemannian metric on the complex plane C. We show that these operators are quasi-compact of ...

37D35 ; 30D35

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- 162 p.
ISBN 978-0-521-43593-2

London mathematical society lecture note series , 0180

Localisation : Collection 1er étage

difféomorphisme # ensemble de Pesin # entropie # ergodicité # mesure d'invariants # point périodique # structure chaotique # théorie de la mesure # théorie ergodique # variété stable

47A35 ; 58F11

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- 267 p.
ISBN

Astérisque , 0187

Localisation : Périodique 1er étage

équation différentielle ordinaire # fonction zêta # système dynamique

58Fxx

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- viii; 281 p.
ISBN 978-2-85629-818-3

Astérisque , 0373

Localisation : Périodique 1er étage

flot géodésique # courbure négative # état de Gibbs # période # dénombrement d'orbites # densité de Patterson # pression # principe variationnel # foliation instable et forte

37D35 ; 53D25 ; 37D40 ; 37A25 ; 37C35 ; 53C12

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