NEW ADVANCES in SYMBOLIC DYNAMICS Bryna Kra. Symbolic
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CURRENT EVENTS BULLETIN Friday, January 8, 2016, 1:00 PM to 5:00 PM Room 4C-3 Washington State Convention Center Joint Mathematics Meetings, Seattle, WA
A MERICAN M ATHEMATICAL S OCIETY CURRENT EVENTS BULLETIN Friday, January 8, 2016, 1:00 PM to 5:00 PM Room 4C-3 Washington State Convention Center Joint Mathematics Meetings, Seattle, WA 1:00 PM Carina Curto, Pennsylvania State University What can topology tell us about the neural code? Surprising new applications of what used to be thought of as “pure” mathematics. 2:00 PM Yuval Peres, Microsoft Research and University of California, Berkeley, and Lionel Levine, Cornell University Laplacian growth, sandpiles and scaling limits Striking large-scale structure arising from simple cellular automata. 3:00 PM Timothy Gowers, Cambridge University Probabilistic combinatorics and the recent work of Peter Keevash The major existence conjecture for combinatorial designs has been proven! 4:00 PM Amie Wilkinson, University of Chicago What are Lyapunov exponents, and why are they interesting? A basic tool in understanding the predictability of physical systems, explained. Organized by David Eisenbud, Mathematical Sciences Research Institute Introduction to the Current Events Bulletin Will the Riemann Hypothesis be proved this week? What is the Geometric Langlands Conjecture about? How could you best exploit a stream of data flowing by too fast to capture? I think we mathematicians are provoked to ask such questions by our sense that underneath the vastness of mathematics is a fundamental unity allowing us to look into many different corners -- though we couldn't possibly work in all of them. I love the idea of having an expert explain such things to me in a brief, accessible way. And I, like most of us, love common-room gossip. -
I. Overview of Activities, April, 2005-March, 2006 …
MATHEMATICAL SCIENCES RESEARCH INSTITUTE ANNUAL REPORT FOR 2005-2006 I. Overview of Activities, April, 2005-March, 2006 …......……………………. 2 Innovations ………………………………………………………..... 2 Scientific Highlights …..…………………………………………… 4 MSRI Experiences ….……………………………………………… 6 II. Programs …………………………………………………………………….. 13 III. Workshops ……………………………………………………………………. 17 IV. Postdoctoral Fellows …………………………………………………………. 19 Papers by Postdoctoral Fellows …………………………………… 21 V. Mathematics Education and Awareness …...………………………………. 23 VI. Industrial Participation ...…………………………………………………… 26 VII. Future Programs …………………………………………………………….. 28 VIII. Collaborations ………………………………………………………………… 30 IX. Papers Reported by Members ………………………………………………. 35 X. Appendix - Final Reports ……………………………………………………. 45 Programs Workshops Summer Graduate Workshops MSRI Network Conferences MATHEMATICAL SCIENCES RESEARCH INSTITUTE ANNUAL REPORT FOR 2005-2006 I. Overview of Activities, April, 2005-March, 2006 This annual report covers MSRI projects and activities that have been concluded since the submission of the last report in May, 2005. This includes the Spring, 2005 semester programs, the 2005 summer graduate workshops, the Fall, 2005 programs and the January and February workshops of Spring, 2006. This report does not contain fiscal or demographic data. Those data will be submitted in the Fall, 2006 final report covering the completed fiscal 2006 year, based on audited financial reports. This report begins with a discussion of MSRI innovations undertaken this year, followed by highlights -
What Are Lyapunov Exponents, and Why Are They Interesting?
BULLETIN (New Series) OF THE AMERICAN MATHEMATICAL SOCIETY Volume 54, Number 1, January 2017, Pages 79–105 http://dx.doi.org/10.1090/bull/1552 Article electronically published on September 6, 2016 WHAT ARE LYAPUNOV EXPONENTS, AND WHY ARE THEY INTERESTING? AMIE WILKINSON Introduction At the 2014 International Congress of Mathematicians in Seoul, South Korea, Franco-Brazilian mathematician Artur Avila was awarded the Fields Medal for “his profound contributions to dynamical systems theory, which have changed the face of the field, using the powerful idea of renormalization as a unifying principle.”1 Although it is not explicitly mentioned in this citation, there is a second unify- ing concept in Avila’s work that is closely tied with renormalization: Lyapunov (or characteristic) exponents. Lyapunov exponents play a key role in three areas of Avila’s research: smooth ergodic theory, billiards and translation surfaces, and the spectral theory of 1-dimensional Schr¨odinger operators. Here we take the op- portunity to explore these areas and reveal some underlying themes connecting exponents, chaotic dynamics and renormalization. But first, what are Lyapunov exponents? Let’s begin by viewing them in one of their natural habitats: the iterated barycentric subdivision of a triangle. When the midpoint of each side of a triangle is connected to its opposite vertex by a line segment, the three resulting segments meet in a point in the interior of the triangle. The barycentric subdivision of a triangle is the collection of 6 smaller triangles determined by these segments and the edges of the original triangle: Figure 1. Barycentric subdivision. Received by the editors August 2, 2016. -
Deterministic Brownian Motion: the Effects of Perturbing a Dynamical
1 Deterministic Brownian Motion: The Effects of Perturbing a Dynamical System by a Chaotic Semi-Dynamical System Michael C. Mackey∗and Marta Tyran-Kami´nska † October 26, 2018 Abstract Here we review and extend central limit theorems for highly chaotic but deterministic semi- dynamical discrete time systems. We then apply these results show how Brownian motion-like results are recovered, and how an Ornstein-Uhlenbeck process results within a totally determin- istic framework. These results illustrate that the contamination of experimental data by “noise” may, under certain circumstances, be alternately interpreted as the signature of an underlying chaotic process. Contents 1 Introduction 2 2 Semi-dynamical systems 5 2.1 Density evolution operators . ......... 5 2.2 Probabilistic and ergodic properties of density evolution ................ 12 2.3 Brownian motion from deterministic perturbations . ............... 16 2.3.1 Centrallimittheorems. ..... 16 2.3.2 FCLTfornoninvertiblemaps . ..... 20 2.4 Weak convergence criteria . ........ 31 3 Analysis 33 3.1 Weak convergence of v(tn) and vn. ............................ 35 3.2 Thelinearcaseinonedimension . ........ 36 3.2.1 Behaviour of the velocity variable . ......... 36 3.2.2 Behaviour of the position variable . ........ 38 4 Identifying the Limiting Velocity Distribution 41 4.1 Dyadicmap....................................... 42 arXiv:cond-mat/0408330v1 [cond-mat.stat-mech] 13 Aug 2004 4.2 Graphical illustration of the velocity density evolution with dyadic map perturbations 45 4.3 r-dyadicmap ..................................... 45 ∗e-mail: [email protected], Departments of Physiology, Physics & Mathematics and Centre for Nonlinear Dynamics, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, CANADA, H3G 1Y6 †Corresponding author, email: [email protected], Institute of Mathematics, Silesian University, ul. -
Boshernitzan's Condition, Factor Complexity, and an Application
BOSHERNITZAN’S CONDITION, FACTOR COMPLEXITY, AND AN APPLICATION VAN CYR AND BRYNA KRA Abstract. Boshernitzan found a decay condition on the measure of cylin- der sets that implies unique ergodicity for minimal subshifts. Interest in the properties of subshifts satisfying this condition has grown recently, due to a connection with the study of discrete Schr¨odinger operators. Of particular interest is the question of how restrictive Boshernitzan’s condition is. While it implies zero topological entropy, our main theorem shows how to construct minimal subshifts satisfying the condition whose factor complexity grows faster than any pre-assigned subexponential rate. As an application, via a theorem of Damanik and Lenz, we show that there is no subexponentially growing se- quence for which the spectra of all discrete Schr¨odinger operators associated with subshifts whose complexity grows faster than the given sequence, have only finitely many gaps. 1. Boshernitzan’s complexity conditions For a symbolic dynamical system (X, σ), many of the isomorphism invariants we have are statements about the growth rate of the word complexity function PX (n), which counts the number of distinct cylinder sets determined by words of length n having nonempty intersection with X. For example, the exponential growth of PX (n) is the topological entropy of (X, σ), while the linear growth rate of PX (n) gives an invariant to begin distinguishing between zero entropy systems. Of course there are different senses in which the growth of PX (n) could be said to be linear and different invariants arise from them. For example, one can consider systems with linear limit inferior growth, meaning lim infn→∞ PX (n)/n < ∞, or the stronger condition of linear limit superior growth, meaning lim supn→∞ PX (n)/n < ∞. -
Attractors and Orbit-Flip Homoclinic Orbits for Star Flows
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY Volume 141, Number 8, August 2013, Pages 2783–2791 S 0002-9939(2013)11535-2 Article electronically published on April 12, 2013 ATTRACTORS AND ORBIT-FLIP HOMOCLINIC ORBITS FOR STAR FLOWS C. A. MORALES (Communicated by Bryna Kra) Abstract. We study star flows on closed 3-manifolds and prove that they either have a finite number of attractors or can be C1 approximated by vector fields with orbit-flip homoclinic orbits. 1. Introduction The notion of attractor deserves a fundamental place in the modern theory of dynamical systems. This assertion, supported by the nowadays classical theory of turbulence [27], is enlightened by the recent Palis conjecture [24] about the abun- dance of dynamical systems with finitely many attractors absorbing most positive trajectories. If confirmed, such a conjecture means the understanding of a great part of dynamical systems in the sense of their long-term behaviour. Here we attack a problem which goes straight to the Palis conjecture: The fini- tude of the number of attractors for a given dynamical system. Such a problem has been solved positively under certain circunstances. For instance, we have the work by Lopes [16], who, based upon early works by Ma˜n´e [18] and extending pre- vious ones by Liao [15] and Pliss [25], studied the structure of the C1 structural stable diffeomorphisms and proved the finitude of attractors for such diffeomor- phisms. His work was largely extended by Ma˜n´e himself in the celebrated solution of the C1 stability conjecture [17]. On the other hand, the Japanesse researchers S. -
A Pseudo Random Numbers Generator Based on Chaotic Iterations
A Pseudo Random Numbers Generator Based on Chaotic Iterations. Application to Watermarking Christophe Guyeux, Qianxue Wang, Jacques Bahi To cite this version: Christophe Guyeux, Qianxue Wang, Jacques Bahi. A Pseudo Random Numbers Generator Based on Chaotic Iterations. Application to Watermarking. WISM 2010, Int. Conf. on Web Information Systems and Mining, 2010, China. pp.202–211. hal-00563317 HAL Id: hal-00563317 https://hal.archives-ouvertes.fr/hal-00563317 Submitted on 4 Feb 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. A Pseudo Random Numbers Generator Based on Chaotic Iterations. Application to Watermarking Christophe Guyeux, Qianxue Wang, and Jacques M. Bahi University of Franche-Comte, Computer Science Laboratory LIFC, 25030 Besanc¸on Cedex, France {christophe.guyeux,qianxue.wang, jacques.bahi}@univ-fcomte.fr Abstract. In this paper, a new chaotic pseudo-random number generator (PRNG) is proposed. It combines the well-known ISAAC and XORshift generators with chaotic iterations. This PRNG possesses important properties of topological chaos and can successfully pass NIST and TestU01 batteries of tests. This makes our generator suitable for information security applications like cryptography. As an illustrative example, an application in the field of watermarking is presented. -
Transformations)
TRANSFORMACJE (TRANSFORMATIONS) Transformacje (Transformations) is an interdisciplinary refereed, reviewed journal, published since 1992. The journal is devoted to i.a.: civilizational and cultural transformations, information (knowledge) societies, global problematique, sustainable development, political philosophy and values, future studies. The journal's quasi-paradigm is TRANSFORMATION - as a present stage and form of development of technology, society, culture, civilization, values, mindsets etc. Impacts and potentialities of change and transition need new methodological tools, new visions and innovation for theoretical and practical capacity-building. The journal aims to promote inter-, multi- and transdisci- plinary approach, future orientation and strategic and global thinking. Transformacje (Transformations) are internationally available – since 2012 we have a licence agrement with the global database: EBSCO Publishing (Ipswich, MA, USA) We are listed by INDEX COPERNICUS since 2013 I TRANSFORMACJE(TRANSFORMATIONS) 3-4 (78-79) 2013 ISSN 1230-0292 Reviewed journal Published twice a year (double issues) in Polish and English (separate papers) Editorial Staff: Prof. Lech W. ZACHER, Center of Impact Assessment Studies and Forecasting, Kozminski University, Warsaw, Poland ([email protected]) – Editor-in-Chief Prof. Dora MARINOVA, Sustainability Policy Institute, Curtin University, Perth, Australia ([email protected]) – Deputy Editor-in-Chief Prof. Tadeusz MICZKA, Institute of Cultural and Interdisciplinary Studies, University of Silesia, Katowice, Poland ([email protected]) – Deputy Editor-in-Chief Dr Małgorzata SKÓRZEWSKA-AMBERG, School of Law, Kozminski University, Warsaw, Poland ([email protected]) – Coordinator Dr Alina BETLEJ, Institute of Sociology, John Paul II Catholic University of Lublin, Poland Dr Mirosław GEISE, Institute of Political Sciences, Kazimierz Wielki University, Bydgoszcz, Poland (also statistical editor) Prof. -
On the Topological Conjugacy Problem for Interval Maps
On the topological conjugacy problem for interval maps Roberto Venegeroles1, ∗ 1Centro de Matem´atica, Computa¸c~aoe Cogni¸c~ao,UFABC, 09210-170, Santo Andr´e,SP, Brazil (Dated: November 6, 2018) We propose an inverse approach for dealing with interval maps based on the manner whereby their branches are related (folding property), instead of addressing the map equations as a whole. As a main result, we provide a symmetry-breaking framework for determining topological conjugacy of interval maps, a well-known open problem in ergodic theory. Implications thereof for the spectrum and eigenfunctions of the Perron-Frobenius operator are also discussed. PACS numbers: 05.45.Ac, 02.30.Tb, 02.30.Zz Introduction - From the ergodic point of view, a mea- there exists a homeomorphism ! such that sure describing a chaotic map T is rightly one that, after S ! = ! T: (2) iterate a randomly chosen initial point, the iterates will ◦ ◦ be distributed according to this measure almost surely. Of course, the problem refers to the task of finding !, if This means that such a measure µ, called invariant, is it exists, when T and S are given beforehand. −1 preserved under application of T , i.e., µ[T (A)] = µ(A) Fundamental aspects of chaotic dynamics are pre- for any measurable subset A of the phase space [1, 2]. served under conjugacy. A map is chaotic if is topo- Physical measures are absolutely continuous with respect logical transitive and has sensitive dependence on initial to the Lebesgue measure, i.e., dµ(x) = ρ(x)dx, being the conditions. Both properties are preserved under conju- invariant density ρ(x) an eigenfunction of the Perron- gacy, then T is chaotic if and only if S is also. -
Arxiv:2108.08461V1 [Math.DS] 19 Aug 2021 References 48
THE BOOTSTRAP FOR DYNAMICAL SYSTEMS KASUN FERNANDO AND NAN ZOU Abstract. Despite their deterministic nature, dynamical systems often exhibit seemingly random behaviour. Consequently, a dynamical system is usually represented by a probabilistic model of which the unknown parameters must be estimated using statistical methods. When measuring the uncertainty of such parameter estimation, the bootstrap stands out as a simple but powerful technique. In this paper, we develop the bootstrap for dynamical systems and establish not only its consistency but also its second-order efficiency via a novel continuous Edgeworth expansion for dynamical systems. This is the first time such continuous Edgeworth expansions have been studied. Moreover, we verify the theoretical results about the bootstrap using computer simulations. Contents 1. Introduction 1 2. Notation and Preliminaries5 I Continuous Edgeworth Expansions 7 3. Spectral Assumptions8 4. First-order Continuous Edgeworth Expansions 19 5. Examples 24 II The Bootstrap 33 6. The Bootstrap Algorithm 33 7. Asymptotic Accuracy of the Bootstrap 35 8. Application of the Bootstrap to our Examples 39 9. Computer Simulation of the Bootstrap 42 arXiv:2108.08461v1 [math.DS] 19 Aug 2021 References 48 1. Introduction After its establishment in late 19th century through the efforts of Poincar´e[64] and Lyapunov [49], the theory of dynamical systems was applied to study the qualitative behaviour of dynamical processes in the real world. For example, the theory of dynamical systems has proved useful in, 2010 Mathematics Subject Classification. 62F40, 37A50, 62M05. Key words and phrases. dynamical systems, the bootstrap, continuous Edgeworth expansions, expanding maps, Markov chains. 1 2 KASUN FERNANDO AND NAN ZOU among many others, astronomy [12], chemical engineering [3], biology [51], ecology [74], demography [81], economics [75], language processing [65], neural activity [71], and machine learning [9], [16]. -
Nilpotent Structures in Ergodic Theory
Mathematical Surveys and Monographs Volume 236 Nilpotent Structures in Ergodic Theory Bernard Host Bryna Kra 10.1090/surv/236 Nilpotent Structures in Ergodic Theory Mathematical Surveys and Monographs Volume 236 Nilpotent Structures in Ergodic Theory Bernard Host Bryna Kra EDITORIAL COMMITTEE Walter Craig Natasa Sesum Robert Guralnick, Chair Benjamin Sudakov Constantin Teleman 2010 Mathematics Subject Classification. Primary 37A05, 37A30, 37A45, 37A25, 37B05, 37B20, 11B25,11B30, 28D05, 47A35. For additional information and updates on this book, visit www.ams.org/bookpages/surv-236 Library of Congress Cataloging-in-Publication Data Names: Host, B. (Bernard), author. | Kra, Bryna, 1966– author. Title: Nilpotent structures in ergodic theory / Bernard Host, Bryna Kra. Description: Providence, Rhode Island : American Mathematical Society [2018] | Series: Mathe- matical surveys and monographs; volume 236 | Includes bibliographical references and index. Identifiers: LCCN 2018043934 | ISBN 9781470447809 (alk. paper) Subjects: LCSH: Ergodic theory. | Nilpotent groups. | Isomorphisms (Mathematics) | AMS: Dynamical systems and ergodic theory – Ergodic theory – Measure-preserving transformations. msc | Dynamical systems and ergodic theory – Ergodic theory – Ergodic theorems, spectral theory, Markov operators. msc | Dynamical systems and ergodic theory – Ergodic theory – Relations with number theory and harmonic analysis. msc | Dynamical systems and ergodic theory – Ergodic theory – Ergodicity, mixing, rates of mixing. msc | Dynamical systems and ergodic -
ON the ISOMORPHISM PROBLEM for NON-MINIMAL TRANSFORMATIONS with DISCRETE SPECTRUM Nikolai Edeko (Communicated by Bryna Kra) 1. I
DISCRETE AND CONTINUOUS doi:10.3934/dcds.2019262 DYNAMICAL SYSTEMS Volume 39, Number 10, October 2019 pp. 6001{6021 ON THE ISOMORPHISM PROBLEM FOR NON-MINIMAL TRANSFORMATIONS WITH DISCRETE SPECTRUM Nikolai Edeko Mathematisches Institut, Universit¨atT¨ubingen Auf der Morgenstelle 10 D-72076 T¨ubingen,Germany (Communicated by Bryna Kra) Abstract. The article addresses the isomorphism problem for non-minimal topological dynamical systems with discrete spectrum, giving a solution under appropriate topological constraints. Moreover, it is shown that trivial systems, group rotations and their products, up to factors, make up all systems with discrete spectrum. These results are then translated into corresponding results for non-ergodic measure-preserving systems with discrete spectrum. 1. Introduction. The isomorphism problem is one of the most important prob- lems in the theory of dynamical systems, first formulated by von Neumann in [17, pp. 592{593], his seminal work on the Koopman operator method and on dynamical systems with \pure point spectrum" (or \discrete spectrum"). Von Neumann, in particular, asked whether unitary equivalence of the associated Koopman opera- tors (\spectral isomorphy") implied the existence of a point isomorphism between two systems (\point isomorphy"). In [17, Satz IV.5], he showed that two ergodic measure-preserving dynamical systems with discrete spectrum on standard proba- bility spaces are point isomorphic if and only if the point spectra of their Koopman operators coincide, which in turn is equivalent to their