Analysis Seminar in Crete (2015-16) |
Σεμιναριο Αναλυσης
Analysis Seminars in the World / Analysis seminars in Greece
DATE | TIME | ROOM | SPEAKER | FROM | TITLE | COMMENT |
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Tue, 29 Sep 2015 | 13:45 | A302 | Themis Mitsis | University of Crete | Strong maximal functions and weights | |
Tue, 3 Nov 2015 | 13:15 | A302 | Nikos Frantzikinakis | University of Crete | Ergodic theorems with arithmetic weights. | |
Abstract: We present results with an arithmetic flavor that generalize the polynomial multidimensional Szemeredi theorem and related multiple recurrence and convergence results in ergodic theory. For instance, we show that in all these statements we can restrict the ''common difference'' to those integers that have an even (or an odd) number of distinct prime factors, or satisfy any other such congruence condition. In order to obtain these refinements we study the limiting behavior of some closely related multiple ergodic averages with weights given by appropriately chosen multiplicative functions. These averages are then analyzed using recent structural results for multiple correlation sequences and bounded multiplicative functions. This is joint work with B. Host. | ||||||
Wed, 18 Nov 2015 | 13:15 | A302 | Nikolaos Pattakos | University of Crete | From dyadic estimates to continuous estimates in Harmonic analysis I | |
Abstract: A dyadic weighted estimate is going to be presented for the Martingale transform and then by the use of the Bellman function technique we will pass to an analogous estimate for continuous type operators such as the Hilbert transform and the Riesz transforms. | ||||||
Wed, 2 Dec 2015 | 13:15 | A302 | Nikolaos Pattakos | University of Crete | From dyadic estimates to continuous estimates in Harmonic analysis II | |
Abstract: A dyadic weighted estimate is going to be presented for the Martingale transform and then by the use of the Bellman function technique we will pass to an analogous estimate for continuous type operators such as the Hilbert transform and the Riesz transforms. | ||||||
Tue, 16 Feb 2016 | 13:15 | A302 | Jorge Antezana | Univ. Nacional de la Plata and Instituto Argentino de Matemática "Alberto Calderón" | Convergence of the iterated Aluthge Transform sequence for matrices | |
Abstract: Here in PDF. | ||||||
Tue, 23 Feb 2016 | 13:15 | A302 | Elona Agora | Instituto Argentino de Matemática "Alberto Calderón" | Sufficient conditions for the boundedness of the Riesz transforms on Weighted Lorentz spaces | |
Abstract: Throughout this talk we will discuss an ongoing research on the boundedness of Riesz transforms on Weighted Lorentz spaces. We will present sufficient conditions for this boundedness in terms of the boundedness of the multi-dimensional Hardy-Littlewood maximal operator. Since the Riesz transforms are a natural generalization of the Hilbert transform in several variables, our work has been motivated by recent results on the boundedness of the Hilbert transform on the same spaces. | ||||||
Tue, 15 Mar 2016 | 13:15 | A302 | Georgios Costakis | University of Crete | Kronecker type theorems and dynamics of matrices. | |
Tue, 29 Mar 2016 | 13:15 | A302 | Nikos Dafnis | Technion | An inequality for moments of log-concave functions on Gaussian random vectors | |
Abstract: We prove a sharp moment inequality for a log-concave or a log-convex function, on Gaussian random vectors. As an application we take a stability result for the classical logarithmic Sobolev inequality of L. Gross in the case where the function is log-concave. | ||||||
Tue, 12 Apr 2016 | 13:15 | A302 | Agelos Georgakopoulos | University of Warwick | The planar Cayley graphs are effectively enumerable | |
Abstract: We show [2] that a group admits a planar, finitely generated Cayley graph if and only if it admits a special kind of group presentation we introduce, called a planar presentation. Planar presentations can be recognised algorithmically. As a consequence, we obtain an effective enumeration of the planar Cayley graphs, yielding in particular an affirmative answer to a question of Droms et al. asking whether the planar groups can be effectively enumerated. This builds on the techniques of [1], where the 3-regular planar Cayley graphs have been classified. Joint work with Matthias Hamann.
[1] A. Georgakopoulos. The planar cubic Cayley graphs. To appear in Memoirs of the AMS. |
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Wed, 20 Apr 2016 | 10:15 | A302 | Mihalis Kolountzakis | University of Crete | Some variations of the Steinhaus tiling problem | |
Tue, 28 Jun 2016 | 13:15 | A303 | Jakub Konieczny | University of Oxford | Combinatorial properties of Nil-Bohr sets of integers | |
Abstract: We explore connections between two classes of sets of integers. On one hand, we have the Nil-Bohr sets, which are the natural analogues of Bohr sets in higher order Fourier analysis, and arise from dynamics on nilmanifolds. On the other hand - we have the purely combinatorial property SG*, which is a slight modification of the better known IP*. It was first observed by Host and Kra that the two classes mentioned above are closely connected, in that every SG*-set is piecewise Nil-Bohr. During the talk, a partial converse to this statement will be discussed, leading to a partial combinatorial characterisation of the class of Nil-Bohr sets. As an application, a characterisation of pre-nilsystems in terms of sets of return times will be obtained. | ||||||
Tue, 5 Jul 2016 | 13:15 | A303 | Ioannis Kontoyiannis | Athens Univ of Econ & Business | Sumset and inverse sumset bounds for the entropy | |
Abstract: The development of the field of additive combinatorics
in recent years has provided a collection of fascinating
and deep, though elementary, tools for estimating the
sizes of discrete subsets of abelian groups. Tao in 2010
connected these results with the entropy of discrete
probability measures: Interpreting the entropy of a discrete
random variable as the logarithm of its "effective support
size", he provided a series of new inequalities for the
discrete entropy. We will review this background and
describe how Tao's results extend in a nontrivial way
to the entropy of random elements in general abelian groups.
The (somewhat surprising) key difference between the
discrete and the general case is that the
"functional submodularity" property of the discrete entropy
needs to be replaced by the general "data processing property"
of the entropy.
No background in information theory, entropy or additive combinatorics will be assumed. This is joint work with Mokshay Madiman. |
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Tue, 12 Jul 2016 | 13:15 | A303 | Andreas Koutsogiannis | Ohio State University | On the convergence of multiple correlation sequences with integer part polynomial iterates | |
Abstract: We will discuss known and new results on multiple correlation sequences. More specifically, we will show that multiple ergodic averages with iterates given by the integer part of real valued polynomials converge in the (uniform) mean. The key ingredient is a transference principle that enables one to deduce results for $\mathbb{Z}$-actions, from results for flows. Using the same method, we prove an extension of the multidimensional Szemerédi theorem which involves closest integer polynomials evaluated at the set of shifted primes. |
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