Mathematics

Fubini foiled: pathological foliations from symbolic codings

Speaker: 
Aaron Calderon
Date: 
Tue, Sep 13, 2022
Location: 
Online
Conference: 
Online working seminar in Ergodic Theory
University of Utah Seminar in Ergodic Theory
Abstract: 

In this talk, I'll present a counterintuitive construction of A. Katok (exposited by Milnor) which at first glance seems to contradict Fubini's theorem. In particular, one can build a full-measure set E in the unit square and a foliation of the square by smooth curves such that any leaf of the foliation meets E in exactly one point. If time permits, I'll also mention work of Ruelle-Wilkinson and Shub-Wilkinson that shows these sorts of pathological examples are common in non-uniformly hyperbolic dynamics.

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Subject: 

Agent-based modelling and topological data analysis of zebrafish patterns

Speaker: 
Bjorn Sandstede
Date: 
Wed, Sep 21, 2022
Location: 
PIMS, University of British Columbia
Online
Zoom
Conference: 
Mathematical Biology Seminar
Abstract: 

Patterns are widespread in nature and often form during early development due to the self-organization of cells or other independent agents. One example are zebrafish (Danio rerio): wild-type zebrafish have regular black and gold stripes, while mutants and other fish feature spotty and patchy patterns. Qualitatively, these patterns display impressive consistency and redundancy, yet variability inevitably exists on both microscopic and macroscopic scales. I will first discuss an agent-based model that suggests that both consistency and richness of patterning on zebrafish stems from the presence of redundancy in iridophore interactions. In the second part of my talk, I will focus on how we can quantify features and variability of patterns to facilitate predictive analyses. I will discuss an approach based on topological data analysis for quantifying both agent-level features and global pattern attributes on a large scale. The proposed methodology is able to quantify the differential impact of stochasticity in cell interactions on wild-type and mutant patterns and predicts stripe and spot statistics as a function of varying cellular communication. This is joint work with Alexandria Volkening and Melissa McGuirl.

Class: 

No IET is Mixing

Speaker: 
Gianluca Faraco
Date: 
Tue, Sep 6, 2022
Location: 
University of Utah
Online
Conference: 
Online working seminar in Ergodic Theory
University of Utah Seminar in Ergodic Theory
Abstract: 

In 1980, Katok proved that no interval exchange transformation (IET) is mixing for any Borel invariant measure. The same holds for any special flow constructed by mean of any IET and a roof function of bounded variation. In this talk, I aim to explain to you the proof of these results.

Class: 
Subject: 

Statistical Estimation with Differential Privacy

Speaker: 
Gautam Kamath
Date: 
Thu, Aug 25, 2022
Location: 
PIMS, University of Victoria
Conference: 
Mathematics of Ethical Decision-making Systems
Abstract: 

Naively implemented, statistical procedures are prone to leaking information about their training data, which can be problematic if the data is sensitive. Differential privacy, a rigorous notion of data privacy, offers a principled framework to dealing with these issues. I will survey recent results in differential private statistical estimation, presenting a few vignettes which highlight novel challenges for even the most fundamental problems, and suggesting solutions to address them. Along the way, I’ll mention connections to tools and techniques in a number of fields, including information theory and robust statistics.

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Subject: 

Furstenberg's topological x2 x3 result

Speaker: 
Barak Weiss
Date: 
Tue, Aug 16, 2022
Location: 
University of Utah
Zoom
Conference: 
Online working seminar in Ergodic Theory
University of Utah Seminar in Ergodic Theory
Abstract: 

In 1967 Furstenberg proved that any closed subset of the one dimensional torus R/Z, invariant under the two maps x -> 2x mod 1, x -> 3x mod 1, is either finite or the entire torus. I will explain a proof of this result due to Boshernitzan (1994). Furstenberg's proof is slightly longer but perhaps more conceptual. I will explain the main steps in Furstenberg's approach and their connection to joinings.

Class: 
Subject: 

Floer Homology Applications 3

Speaker: 
Jeff Hicks
Date: 
Fri, Jul 22, 2022
Location: 
PIMS, University of British Columbia, Zoom, Online
Conference: 
Séminaire de Mathématiques Supérieures 2022: Floer Homotopy Theory
Abstract: 

A lecture titled "Floer Homology Applications" by Jeff Hicks, University of Edinburgh. This is the 3rd in a series of 3.

General Description:
The idea of stable homotopy refinements of Floer homology was first introduced by Cohen, Jones, and Segal in a 1994 paper, but it was only in the last decade that this idea became a key tool in low-dimensional and symplectic topology. The two crowning achievements of these techniques so far are Manolescu's use of his Pin(2)-equivariant Seiberg–Witten Floer homotopy type to resolve the Triangulation Conjecture and Abouzaid-Blumberg's use of Floer homotopy theory and Morava K-theory to prove the general Arnol'd Conjecture in finite characteristic. During this period, a range of related techniques, included under the umbrella of Floer homotopy theory, have also led to important advances, including involutive Heegaard Floer homology, Smith theory for Lagrangian intersections, homotopy coherence, and further connections between string topology and Floer theory. These in turn have sparked developments in algebraic topology, ranging from developments on Lie algebras in derived algebraic geometry to new computations of equivariant Mahowald invariants to new results on topological Hochschild homology.

The goal of the summer school is to provide participants the tools in symplectic geometry and stable homotopy theory required to work on Floer homotopy theory. Students will come away with a basic understanding of some of the key techniques, questions, and challenges in both of these fields. The summer school may be particularly valuable for participants with a solid understanding of one of the two fields who want to learn more about the other and the connections between them.

Class: 
Subject: 

Spectra and Smash Products 4

Speaker: 
Cary Malkiewich
Date: 
Fri, Jul 22, 2022
Location: 
PIMS, University of British Columbia, Zoom, Online
Conference: 
Séminaire de Mathématiques Supérieures 2022: Floer Homotopy Theory
Abstract: 

A lecture titled "Spectra and Smash Products" by Cary Malkiewich, Binghamton University. This is the 4th in a series of 4.

General Description:
The idea of stable homotopy refinements of Floer homology was first introduced by Cohen, Jones, and Segal in a 1994 paper, but it was only in the last decade that this idea became a key tool in low-dimensional and symplectic topology. The two crowning achievements of these techniques so far are Manolescu's use of his Pin(2)-equivariant Seiberg–Witten Floer homotopy type to resolve the Triangulation Conjecture and Abouzaid-Blumberg's use of Floer homotopy theory and Morava K-theory to prove the general Arnol'd Conjecture in finite characteristic. During this period, a range of related techniques, included under the umbrella of Floer homotopy theory, have also led to important advances, including involutive Heegaard Floer homology, Smith theory for Lagrangian intersections, homotopy coherence, and further connections between string topology and Floer theory. These in turn have sparked developments in algebraic topology, ranging from developments on Lie algebras in derived algebraic geometry to new computations of equivariant Mahowald invariants to new results on topological Hochschild homology.

The goal of the summer school is to provide participants the tools in symplectic geometry and stable homotopy theory required to work on Floer homotopy theory. Students will come away with a basic understanding of some of the key techniques, questions, and challenges in both of these fields. The summer school may be particularly valuable for participants with a solid understanding of one of the two fields who want to learn more about the other and the connections between them.

Class: 
Subject: 

Floer Homology Fundamentals 5

Speaker: 
Catherine Cannizzo
Date: 
Wed, Jul 13, 2022
Location: 
PIMS, University of British Columbia, Zoom, Online
Conference: 
Séminaire de Mathématiques Supérieures 2022: Floer Homotopy Theory
Abstract: 

A lecture titled "Floer Homology Fundamentals" by Catherine Cannizzo, SCGP. This is the 5th in a series of 9.

General Description:
The idea of stable homotopy refinements of Floer homology was first introduced by Cohen, Jones, and Segal in a 1994 paper, but it was only in the last decade that this idea became a key tool in low-dimensional and symplectic topology. The two crowning achievements of these techniques so far are Manolescu's use of his Pin(2)-equivariant Seiberg–Witten Floer homotopy type to resolve the Triangulation Conjecture and Abouzaid-Blumberg's use of Floer homotopy theory and Morava K-theory to prove the general Arnol'd Conjecture in finite characteristic. During this period, a range of related techniques, included under the umbrella of Floer homotopy theory, have also led to important advances, including involutive Heegaard Floer homology, Smith theory for Lagrangian intersections, homotopy coherence, and further connections between string topology and Floer theory. These in turn have sparked developments in algebraic topology, ranging from developments on Lie algebras in derived algebraic geometry to new computations of equivariant Mahowald invariants to new results on topological Hochschild homology.

The goal of the summer school is to provide participants the tools in symplectic geometry and stable homotopy theory required to work on Floer homotopy theory. Students will come away with a basic understanding of some of the key techniques, questions, and challenges in both of these fields. The summer school may be particularly valuable for participants with a solid understanding of one of the two fields who want to learn more about the other and the connections between them.

Class: 
Subject: 

String Topology 1

Speaker: 
Katherine Poirier
Date: 
Tue, Jul 12, 2022
Location: 
PIMS, University of British Columbia, Zoom, Online
Conference: 
Séminaire de Mathématiques Supérieures 2022: Floer Homotopy Theory
Abstract: 

A lecture titled "String Topology" by Katherine Poirier, New York City College of Technology. This is the 1st in a series of 3.

General Description:
The idea of stable homotopy refinements of Floer homology was first introduced by Cohen, Jones, and Segal in a 1994 paper, but it was only in the last decade that this idea became a key tool in low-dimensional and symplectic topology. The two crowning achievements of these techniques so far are Manolescu's use of his Pin(2)-equivariant Seiberg–Witten Floer homotopy type to resolve the Triangulation Conjecture and Abouzaid-Blumberg's use of Floer homotopy theory and Morava K-theory to prove the general Arnol'd Conjecture in finite characteristic. During this period, a range of related techniques, included under the umbrella of Floer homotopy theory, have also led to important advances, including involutive Heegaard Floer homology, Smith theory for Lagrangian intersections, homotopy coherence, and further connections between string topology and Floer theory. These in turn have sparked developments in algebraic topology, ranging from developments on Lie algebras in derived algebraic geometry to new computations of equivariant Mahowald invariants to new results on topological Hochschild homology.

The goal of the summer school is to provide participants the tools in symplectic geometry and stable homotopy theory required to work on Floer homotopy theory. Students will come away with a basic understanding of some of the key techniques, questions, and challenges in both of these fields. The summer school may be particularly valuable for participants with a solid understanding of one of the two fields who want to learn more about the other and the connections between them.

Class: 
Subject: 

Floer Homology Fundamentals 3

Speaker: 
Catherine Cannizzo
Date: 
Tue, Jul 12, 2022
Location: 
PIMS, University of British Columbia, Zoom, Online
Conference: 
Séminaire de Mathématiques Supérieures 2022: Floer Homotopy Theory
Abstract: 

A lecture titled "Floer Homology Fundamentals" by Catherine Cannizzo, SCGP. This is the 3rd in a series of 9.

General Description:
The idea of stable homotopy refinements of Floer homology was first introduced by Cohen, Jones, and Segal in a 1994 paper, but it was only in the last decade that this idea became a key tool in low-dimensional and symplectic topology. The two crowning achievements of these techniques so far are Manolescu's use of his Pin(2)-equivariant Seiberg–Witten Floer homotopy type to resolve the Triangulation Conjecture and Abouzaid-Blumberg's use of Floer homotopy theory and Morava K-theory to prove the general Arnol'd Conjecture in finite characteristic. During this period, a range of related techniques, included under the umbrella of Floer homotopy theory, have also led to important advances, including involutive Heegaard Floer homology, Smith theory for Lagrangian intersections, homotopy coherence, and further connections between string topology and Floer theory. These in turn have sparked developments in algebraic topology, ranging from developments on Lie algebras in derived algebraic geometry to new computations of equivariant Mahowald invariants to new results on topological Hochschild homology.

The goal of the summer school is to provide participants the tools in symplectic geometry and stable homotopy theory required to work on Floer homotopy theory. Students will come away with a basic understanding of some of the key techniques, questions, and challenges in both of these fields. The summer school may be particularly valuable for participants with a solid understanding of one of the two fields who want to learn more about the other and the connections between them.

Class: 
Subject: 

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