Fall 2021 and Spring 2022 Analysis Seminars

Analysis Seminar

The seminar will meet Tuesdays, 4:00 p.m. in VV B139, unless otherwise indicated.

If you wish to invite a speaker please contact Betsy at stovall(at)math

Summer/Fall 2017 Analysis Seminar Schedule

date	speaker	institution	title	host(s)
September 8 in B239	Tess Anderson	UW Madison	A Spherical Maximal Function along the Primes	Tonghai
September 19	Brian Street	UW Madison	Convenient Coordinates	Betsy
September 26	Hiroyoshi Mitake	Hiroshima University	Derivation of multi-layered interface system and its application	Hung
October 3	Joris Roos	UW Madison	A polynomial Roth theorem on the real line	Betsy
October 10	Michael Greenblatt	UI Chicago	Maximal averages and Radon transforms for two-dimensional hypersurfaces	Andreas
October 17	David Beltran	Basque Center of Applied Mathematics	Fefferman-Stein inequalities	Andreas
Wednesday, October 18, 4:00 p.m. in B131	Jonathan Hickman	University of Chicago	Factorising X^n	Andreas
October 24	Xiaochun Li	UIUC	Recent progress on the pointwise convergence problems of Schroedinger equations	Betsy
Thursday, October 26, 4:30 p.m. in B139	Fedya Nazarov	Kent State University	Title	Betsy, Andreas
Friday, October 27, 4:00 p.m. in B239	Stefanie Petermichl	University of Toulouse	Title	Betsy, Andreas
Wednesday, November 1, 4:00 p.m. in B239	Shaoming Guo	Indiana University	Title	Andreas
November 14	Naser Talebizadeh Sardari	UW Madison	Quadratic forms and the semiclassical eigenfunction hypothesis	Betsy
November 28	Xianghong Chen	UW Milwaukee	Title	Betsy
December 5	Tentatively reserved by Betsy (10/1)		Title
December 12	Alex Stokolos	GA Southern	Title	Andreas

Abstracts

Brian Street

Title: Convenient Coordinates

Abstract: We discuss the method of picking a convenient coordinate system adapted to vector fields. Let X_1,...,X_q be either real or complex C^1 vector fields. We discuss the question of when there is a coordinate system in which the vector fields are smoother (e.g., C^m, or C^\infty, or real analytic). By answering this in a quantitative way, we obtain coordinate charts which can be used as generalized scaling maps. When the vector fields are real this is joint work with Stovall, and continues in the line of quantitative sub-Riemannian geometry initiated by Nagel, Stein, and Wainger. When the vector fields are complex one obtains a geometry with more structure which can be thought of as "sub-Hermitian".

Hiroyoshi Mitake

Title: Derivation of multi-layered interface system and its application

Abstract: In this talk, I will propose a multi-layered interface system which can be formally derived by the singular limit of the weakly coupled system of the Allen-Cahn equation. By using the level set approach, this system can be written as a quasi-monotone degenerate parabolic system. We give results of the well-posedness of viscosity solutions, and study the singularity of each layers. This is a joint work with H. Ninomiya, K. Todoroki.

Joris Roos

Title: A polynomial Roth theorem on the real line

Abstract: For a polynomial P of degree greater than one, we show the existence of patterns of the form (x,x+t,x+P(t)) with a gap estimate on t in positive density subsets of the reals. This is an extension of an earlier result of Bourgain. Our proof is a combination of Bourgain’s approach and more recent methods that were originally developed for the study of the bilinear Hilbert transform along curves. This talk is based on a joint work with Polona Durcik and Shaoming Guo.

Michael Greenblatt

Title: Maximal averages and Radon transforms for two-dimensional hypersurfaces

Abstract: A general local result concerning L^p boundedness of maximal averages over 2D hypersurfaces is described, where p > 2. The surfaces are allowed to have either the traditional smooth density function or a singularity growing as |(x,y)|^{-t} for some 0 < t < 2. This result is a generalization of a theorem of Ikromov, Kempe, and Mueller. Similar methods can be used to show sharp L^p to L^p_a Sobolev estimates for associated Radon transform operators when p is in a certain interval containing 2.

David Beltran

Title: Fefferman Stein Inequalities

Abstract: Given an operator T, we focus on obtaining two-weighted inequalities in which the weights are related via certain maximal function. These inequalites, which originated in work of Fefferman and Stein, have been established in an optimal way for different classical operators in Harmonic Analysis. In this talk, we survey some classical results and we present some recent Fefferman-Stein inequalities for pseudodifferential operators and for the solution operators to dispersive equations.

Jonathan Hickman

Title: Factorising X^n.

Question: how many ways can the polynomial $X^n$ be factorised as a product of linear factors? Answer: it depends on the ring... In this talk I will describe joint work with Jim Wright investigating certain exponential sum estimates over rings of integers modulo N. This theory serves as a discrete analogue of the (euclidean) Fourier restriction problem, a central question in contemporary harmonic analysis. In particular, as part of this study, the question of counting the number of factorisations of polynomials over such rings naturally arises. I will describe how these number-theoretic considerations can themselves be approached via methods from harmonic analysis.

Xiaochun Li

Title: Recent progress on the pointwise convergence problems of Schrodinger equations

Abstract: Recently, Guth, Du and I solved the pointwise convergence problem of Schrodinger equations in two-dimensional case. We proved that the solution to free Schrodinger equation in R^2 converges to its initial data, provided the initial data belongs to H^s for s larger than 1/3. This result is sharp, up to the end point, due to Bourgain's example. The proof relies on the polynomial partitioning method and the decoupling method. In addition, the pointwise convergence problem is closely related to Fourier restriction conjecture.

Naser Talebizadeh Sardari

Title: Quadratic forms and the semiclassical eigenfunction hypothesis

Abstract: Let [math]\displaystyle{ Q(X) }[/math] be any integral primitive positive definite quadratic form in [math]\displaystyle{ k }[/math] variables, where [math]\displaystyle{ k\geq4 }[/math], and discriminant [math]\displaystyle{ D }[/math]. For any integer [math]\displaystyle{ n }[/math], we give an upper bound on the number of integral solutions of [math]\displaystyle{ Q(X)=n }[/math] in terms of [math]\displaystyle{ n }[/math], [math]\displaystyle{ k }[/math], and [math]\displaystyle{ D }[/math]. As a corollary, we prove a conjecture of Lester and Rudnick on the small scale equidistribution of almost all functions belonging to any orthonormal basis of a given eigenspace of the Laplacian on the flat torus [math]\displaystyle{ \mathbb{T}^d }[/math] for [math]\displaystyle{ d\geq 5 }[/math]. This conjecture is motivated by the work of Berry\cite{Berry, Michael} on semiclassical eigenfunction hypothesis.

Extras

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