Fall 2021 and Spring 2022 Analysis Seminars: Difference between revisions

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!align="left" | host(s)
!align="left" | host(s)
|-
|-
|September 21
|September 21, VV B139
| Dóminique Kemp
| Dóminique Kemp
| UW-Madison
| UW-Madison
|[[#linktoabstract |  Decoupling by way of approximation ]]
|[[#Dóminique Kemp |  Decoupling by way of approximation ]]
| Sponsor
|  
|-
|-
|September 28
|September 28, VV B139
| Jack Burkart
| Jack Burkart
| UW-Madison
| UW-Madison
|[[#linktoabstract Title ]]
|[[#Jack Burkart Transcendental Julia Sets with Fractional Packing Dimension ]]
| Sponsor
|  
|-
|-
|October 5
|October 5, Online
| Giuseppe Negro
| Giuseppe Negro
| University of Birmingham
| University of Birmingham
|[[#linktoabstract Title ]]
|[[#Giuseppe Negro Stability of sharp Fourier restriction to spheres ]]
| Sponsor
|  
|-
|-
|October 12
|October 12, VV B139
|Rajula Srivastava
|Rajula Srivastava
|UW Madison
|UW Madison
|[[#linktoabstract  |  Title ]]
|[[#linktoabstract  |  Title ]]
| Sponsor
|  
|-
|-
|October 19
|October 19, Online
|Itamar Oliveira
|Itamar Oliveira
|Cornell University  
|Cornell University  
|[[#linktoabstract  |  Title ]]
|[[#linktoabstract  |  Title ]]
| Sponsor
|  
|-
|-
|October 26
|October 26, VV B139
| Person
| Changkeun Oh
| Institution
| UW Madison
|[[#linktoabstract  |  Title ]]
|[[#linktoabstract  |  Title ]]
| Sponsor
|  
|-
|-
|November 2
|November 2, VV B139
| Person
| Liding Yao
| Institution
| UW Madison
|[[#linktoabstract  |  Title ]]
|[[#linktoabstract  |  Title ]]
| Sponsor
|  
|-
|-
|November 9
|November 9, VV B139
| Person
| Lingxiao Zhang
| Institution
| UW Madison
|[[#linktoabstract  |  Title ]]
|[[#linktoabstract  |  Title ]]
| Sponsor
|  
|-
|-
|November 16
|November 16, VV B139
| Rahul Parhi
| Rahul Parhi
| UW Madison (EE)
| UW Madison (EE)
|[[#linktoabstract  |  Title ]]
|[[#linktoabstract  |  Title ]]
| Sponsor
|  
|-
|-
|November 30
|November 30, VV B139
| Person
| Alexei Poltoratski
| Institution
| UW Madison
|[[#linktoabstract  |  Title ]]
|[[#linktoabstract  |  Title ]]
| Sponsor
|  
|-
|-
|December 7
|December 7
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| Institution
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|[[#linktoabstract  |  Title ]]
| Sponsor
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|December 14
|December 14
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| Institution
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|[[#linktoabstract  |  Title ]]
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Since Bourgain and Demeter's seminal 2017 decoupling result for nondegenerate hypersurfaces, several attempts have been made to extend the theory to degenerate hypersurfaces $M$. In this talk, we will discuss using surfaces derived from the local Taylor expansions of $M$ in order to obtain "approximate" decoupling results. By themselves, these approximate decouplings do not avail much. However, upon considerate iteration, for a specifically chosen $M$, they culminate in a decoupling partition of $M$ into caps small enough either as originally desired or otherwise genuinely nondegenerate at the local scale. A key feature that will be discussed is the notion of approximating a non-convex hypersurface $M$ by convex hypersurfaces at various scales. In this manner, contrary to initial intuition, non-trivial $\ell^2$ decoupling results will be obtained for $M$.
Since Bourgain and Demeter's seminal 2017 decoupling result for nondegenerate hypersurfaces, several attempts have been made to extend the theory to degenerate hypersurfaces $M$. In this talk, we will discuss using surfaces derived from the local Taylor expansions of $M$ in order to obtain "approximate" decoupling results. By themselves, these approximate decouplings do not avail much. However, upon considerate iteration, for a specifically chosen $M$, they culminate in a decoupling partition of $M$ into caps small enough either as originally desired or otherwise genuinely nondegenerate at the local scale. A key feature that will be discussed is the notion of approximating a non-convex hypersurface $M$ by convex hypersurfaces at various scales. In this manner, contrary to initial intuition, non-trivial $\ell^2$ decoupling results will be obtained for $M$.


===Name===
===Jack Burkart===


Title
Transcendental Julia Sets with Fractional Packing Dimension


Abstract
If f is an entire function, the Julia set of f is the set of all points such that f and its iterates locally do not form a normal family; nearby points have very different orbits under iteration by f. A topic of interest in complex dynamics is studying the fractal geometry of the Julia set.


In this talk, we will discuss my thesis result where I construct non-polynomial (transcendental) entire functions whose Julia set has packing dimension strictly between (1,2). We will introduce various notions of dimension and basic objects in complex dynamics, and discuss a history of dimension results in complex dynamics. We will discuss some key aspects of the proof, which include a use of Whitney decompositions of domains as a tool to calculate the packing dimension, and some open questions I am thinking about.


===Name===
===Giuseppe Negro===


Title
Stability of sharp Fourier restriction to spheres


Abstract
In dimension $d\in\{3, 4, 5, 6, 7\}$, we establish that the constant functions maximize the weighted $L^2(S^{d-1}) - L^4(R^d)$ Fourier extension estimate on the sphere, provided that the weight function is sufficiently regular and small, in a proper and effective sense which we will make precise. One of the main tools is an integration by parts identity, which generalizes the so-called "magic identity" of Foschi for the unweighted inequality with $d=3$, which is exactly the classical Stein-Tomas estimate.


Joint work with E.Carneiro and D.Oliveira e Silva.


===Name===
===Name===

Revision as of 05:03, 27 September 2021

The 2021-2022 Analysis Seminar will be organized by David Beltran and Andreas Seeger. Some of the talks will be in person (room Van Vleck B139) and some will be online. The regular time for the Seminar will be Tuesdays at 4:00 p.m. (in some cases we will schedule the seminar at different times, to accommodate speakers).

Zoom links will be sent to those who have signed up for the Analysis Seminar List. If you would like to subscribe to the Analysis seminar list, send a blank email to analysis+join (at) g-groups (dot) wisc (dot) edu. If you are from an institution different than UW-Madison, please send as well as an additional email to David and Andreas (dbeltran, seeger at math (dot) wisc (dot) edu) to notify the request.

If you'd like to suggest speakers for the fall semester please contact David and Andreas.

Analysis Seminar Schedule

date speaker institution title host(s)
September 21, VV B139 Dóminique Kemp UW-Madison Decoupling by way of approximation
September 28, VV B139 Jack Burkart UW-Madison Transcendental Julia Sets with Fractional Packing Dimension
October 5, Online Giuseppe Negro University of Birmingham Stability of sharp Fourier restriction to spheres
October 12, VV B139 Rajula Srivastava UW Madison Title
October 19, Online Itamar Oliveira Cornell University Title
October 26, VV B139 Changkeun Oh UW Madison Title
November 2, VV B139 Liding Yao UW Madison Title
November 9, VV B139 Lingxiao Zhang UW Madison Title
November 16, VV B139 Rahul Parhi UW Madison (EE) Title
November 30, VV B139 Alexei Poltoratski UW Madison Title
December 7 Person Institution Title
December 14 Person Institution Title
Date Person Institution Title

Abstracts

Dóminique Kemp

Decoupling by way of approximation

Since Bourgain and Demeter's seminal 2017 decoupling result for nondegenerate hypersurfaces, several attempts have been made to extend the theory to degenerate hypersurfaces $M$. In this talk, we will discuss using surfaces derived from the local Taylor expansions of $M$ in order to obtain "approximate" decoupling results. By themselves, these approximate decouplings do not avail much. However, upon considerate iteration, for a specifically chosen $M$, they culminate in a decoupling partition of $M$ into caps small enough either as originally desired or otherwise genuinely nondegenerate at the local scale. A key feature that will be discussed is the notion of approximating a non-convex hypersurface $M$ by convex hypersurfaces at various scales. In this manner, contrary to initial intuition, non-trivial $\ell^2$ decoupling results will be obtained for $M$.

Jack Burkart

Transcendental Julia Sets with Fractional Packing Dimension

If f is an entire function, the Julia set of f is the set of all points such that f and its iterates locally do not form a normal family; nearby points have very different orbits under iteration by f. A topic of interest in complex dynamics is studying the fractal geometry of the Julia set.

In this talk, we will discuss my thesis result where I construct non-polynomial (transcendental) entire functions whose Julia set has packing dimension strictly between (1,2). We will introduce various notions of dimension and basic objects in complex dynamics, and discuss a history of dimension results in complex dynamics. We will discuss some key aspects of the proof, which include a use of Whitney decompositions of domains as a tool to calculate the packing dimension, and some open questions I am thinking about.

Giuseppe Negro

Stability of sharp Fourier restriction to spheres

In dimension $d\in\{3, 4, 5, 6, 7\}$, we establish that the constant functions maximize the weighted $L^2(S^{d-1}) - L^4(R^d)$ Fourier extension estimate on the sphere, provided that the weight function is sufficiently regular and small, in a proper and effective sense which we will make precise. One of the main tools is an integration by parts identity, which generalizes the so-called "magic identity" of Foschi for the unweighted inequality with $d=3$, which is exactly the classical Stein-Tomas estimate.

Joint work with E.Carneiro and D.Oliveira e Silva.

Name

Title

Abstract


Name

Title

Abstract






Previous_Analysis_seminars

https://www.math.wisc.edu/wiki/index.php/Previous_Analysis_seminars

Extras

Blank Analysis Seminar Template


Graduate Student Seminar:

https://www.math.wisc.edu/~sguo223/2020Fall_graduate_seminar.html