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Events This Week

Week of September 30 - September 26

 

Friday, September 30

Graduate Colloquium

Topic: The Mathematics of Musical Tuning

Peter Marcus - Tulane University

Abstract: Designers of musical instruments need to decide how they will be tuned, meaning what pitches the instrument can produce. Today the most common tuning system by far is 12-tone equal temperament, but how was this chosen and why is it so popular? I will give a brief history of European tuning systems and dive into the math behind them.

Location: Stanley Thomas 316
Time: 4:00pm Friday THIS IS A DIFFERENT DAY AND TIME

 

 

Monday, September 26

Joint AG & GT Seminar

Topic: From integrals to combinatorial formulas of finite type invariants - a case study.

Rafal Komendarczyk  | Tulane University

Abstract:

We obtain a localized version of the configuration space integral for the Casson knot invariant, where the standard symmetric Gauss form is replaced with a locally supported form. An interesting technical difference between the argument presented here and the classical arguments is that the vanishing of integrals over hidden faces does not require the involution trick due to Kontsevich. The integral formula yields the well-known arrow diagram expression for the
invariant, first presented in the work of Polyak and Viro. We also take the next step of extending the arrow diagram expression to multicrossing knot diagrams. The primary motivation is to better understand a connection between the classical configuration space integrals and arrow diagram formulas for finite type invariants. This is a joint work with Robyn Brooks, which builds on her thesis.

Location: Dinwiddie 103
Time: 3:00pm

 

Week of September 24 - September 19

 

Tuesday, September 19

Joint AG & GT Seminar

Topic: From integrals to combinatorial formulas of finite type invariants - a case study.

Rafal Komendarczyk  | Tulane University

Abstract:

We obtain a localized version of the configuration space integral for the Casson knot invariant, where the standard symmetric Gauss form is replaced with a locally supported form. An interesting technical difference between the argument presented here and the classical arguments is that the vanishing of integrals over hidden faces does not require the involution trick due to Kontsevich. The integral formula yields the well-known arrow diagram expression for the
invariant, first presented in the work of Polyak and Viro. We also take the next step of extending the arrow diagram expression to multicrossing knot diagrams. The primary motivation is to better understand a connection between the classical configuration space integrals and arrow diagram formulas for finite type invariants. This is a joint work with Robyn Brooks, which builds on her thesis.

Location: Dinwiddie 103
Time: 3:00pm

 

Wednesday, September 21

AMS/AWM

Topic: Wavelet random matrices and fractals in high dimensions

Gustavo Didier | Tulane University

Abstract: Scale invariance, or fractality, is a fundamental feature of the long term behavior of many stochastic systems. The study of fractality in high dimensions is a frontier subject in the field of probability theory, and one which impacts several fields of application. In this talk, we show that wavelet random matrices provide a natural framework for the study of scale invariance in high dimensions. No background on the subject will be assumed.

Location: Gibson Hall 126A
Time: We will be following the Algebra and Combinatorics Seminar

 

Wednesday, September 21

Algebra and Combinatorics

Topic: Weakly Complete Universal Enveloping Algebras of Profinite-Dimensional Lie Algebras

Karl Hofmann | Tulane University

 

Location: Gibson 126A
Time: 3:00 pm

 

 

Tuesday, September 20

Graduate Colloquium

Topic: Shor's Algorithm and Quantum Supremacy

Rubaiyat Islam | Tulane University

Abstract: Shor's algorithm is a quantum computing algorithm which shows that a programmable quantum computer can factor integers in polynomial time. Currently used important cryptographic algorithms critically depend on the fact that prime factorization of large numbers with classical algorithms takes a long time. A factoring problem can be turned into a period finding problem and the quantum part of Shor's algorithm significantly speeds up this period finding step. In this talk, we will look at the relation between the two problems, what gives quantum advantage and try to see some output from an actual quantum computer.

Location: Stanley Thomas 316
Time: 5:00pm

 

Week of September 16 - September 12

Friday, September 16

Applied and Computational Math Seminar

Topic: Modeling aspects of vesicle electrodeformation and transport

Adnan Morshed | Tulane University

Abstract: Characterization of the mechanical properties of cells and other sub-micron vesicles such as virus and neurotransmitter vesicles are necessary to understand their deformation dynamics. This characterization can be done by submerging the vesicle in a fluid medium and deforming it with controlled electric field exposure known as electrodeformation. Electrodeformation of biological and artificial lipid vesicles is directly influenced by the vesicle and media properties and geometric factors. The problem is compounded when the vesicle is naturally charged which creates electrophoretic forcing on the vesicle membrane. This talk will highlight some of the modeling aspects of electrodeformation and transport of charged vesicles immersed in a fluid media under the influence of a DC electric field. The electric field and fluid-solid interactions are resolved using a hybrid immersed interface-immersed boundary technique. Viability of the width averaged domain conductivity and current as indicators of vesicle deformation and movement will be discussed. Vesicle movement due to electrophoresis is also characterized by the change in local conductivity which can serve as a potential sensor for electrodeformation experiments and in solid-state nanopore applications.

Location: Gibson 325
Time: 3:00pm

 

Wednesday, September 14

Algebra and Combinatorics

Topic: Generalized Wilf Conjecture

Naufil Sakran | Tulane University

Abstract: The Wilf Conjecture is a longstanding conjecture regarding the complement finite submonoids of N, the monoid of natural numbers. There have been several attempts to generalize the conjecture for higher dimensions. In this talk, we will extend the conjecture for complement finite submonoids of unipotent group with entries from N. This extension gives a better bound compared to the previous generalizations. Also, we will prove our conjecture for certain subfamilies (thick and thin) of the unipotent groups.

Location: Gibson 126A
Time: 3:00 pm

 

Tuesday, September 13

Graduate Colloquium

Topic: Hilbert's 17th Problem

Naufil Sakran | Tulane University

Abstract: Hilbert proposed 23 questions in 1900 at the conference of the International Congress of Mathematics. Answers to these questions have high influence in Modern Mathematics. Hilbert's 17 problem asks about the minimal requirement to a polynomial so that it has representation as sum of squares. The talk will focus on answering the question. Finally, we will discuss open problems regarding it.

Location: Stanley Thomas 316
Time: 5:00pm

 

Monday, September 12

AMS/AWM

Topic: we welcome Dr. Samuel Punshon-Smith

Samuel Punshon-Smith | Tulane University

Abstract: We welcome Dr. Samuel Punshon-Smith to discuss his research and highlight a woman in Mathematics of his choice.  

Location: Gibson Hall 400D
Time: 3:00pm

 

Week of September 9 - September 5

 

Friday, September 9

Applied and Computation Math Seminar

Topic: Microswimmer in confinements

Hongfei Chen | Tulane University

Abstract: We consider the active Brownian particle (ABP) model for a two-dimensional microswimmer with fixed speed, whose direction of swimming changes according to a Brownian process. The probability density for the swimmer obeys a Fokker–Planck equation defined on the configuration space, whose structure depends on the swimmer’s shape, center of rotation and domain of swimming. We enforce zero probability flux at the boundaries of configuration space. We consider the dynamics of a swimmer in an infinite channel and a lattice of point obstacles. At first neglecting hydrodynamic interactions, we derive a reduced equation for a swimmer in an infinite channel, in the limit of small rotational diffusivity, and find that the invariant density depends strongly on the swimmer’s precise shape and center of rotation. We also give a formula for the mean reversal time: the expected time taken for a swimmer to completely reverse direction in the channel. Using homogenization theory, we find an expression for the effective longitudinal diffusivity of a swimmer in the channel, and show that it is bounded by the mean reversal time. Finally, we include hydrodynamic interactions with walls, and examine the role of shape. For a swimmer in a periodic lattice of point obstacles, we apply the same framework as in the channel, solve the invariant density and use the homogenization approach to compute effective diffusivity. Moreover, when the swimmer is only a circular or needle diffuser that cannot swim, we solve the cell problem and effective diffusivity asymptotically.

Location: Gibson 325
Time: 3:00pm

 

Thursday, September 8

Tea Time

Location: Gibson 426

Time: 1:00pm

 

Wednesday, September 7

Algebra and Combinatorics

Topic: Nonlocality and the Pauli Group

Victor Bankston | Tulane University

Abstract: The Pauli group is fundamental in quantum information and is related to certain extraspecial 2-groups. In this talk, I will introduce the Pauli group and pose a novel problem about its structure in terms of partial homomorphisms to products of 2-element groups. Finally, I will motivate the problem by describing a relationship to a novel class of nonlocal games by using the eigenvalue expansion properties of a distance-regular graph.

Location: Gibson 126A
Time: 3:00 pm

 

Tuesday, September 6

Graduate Colloquium

Topic: Projection Method and Linear Algebra

Sang-Eun Lee | Tulane University

Abstract: Due to the millennium problem for the global existence and regularity of the 3D Navier-Stokes equations for the viscous and incompressible flow, we cannot obtain an explicit solution to the system of fluid equations. So, we rely on the computational method to describe and understand fluid motion. There are a few numerical methods to find an approximated solution, but due to the massiveness of the matrix size, people have tried to find to reduce the computational cost of the methods. A well-known method to find the numerical solution of fluid motion is called the projection method, due to Alexandre Chorin. This talk briefly describes the fluid-structure and discusses some linear algebraic skills in each scenario.

Location: Stanley Thomas 316
Time: 5:00pm

 

Week of September 2 - August 29

 

Wednesday, August 30

Algebra and Combinatorics

Topic: Quaternary Lattices, Modular Forms and Elliptic Curves

Daniel Fretwell

Abstract: A common theme in modern Number Theory is to find non-trivial links between objects coming from very different places, by relating their arithmetic. In this talk we will (hopefully) see a surprising example of this, connecting the first and third objects in the title…using the second to bridge the gap. Time permitting, we will sketch the proof, motivated by a hidden 1.5th object (Clifford algebras). (Based on joint work with E. Assaf, C. Ingalls, A. Logan, S. Secord and J. Voight)

Location: DW 103
Time: 3:00pm

 

Tuesday, August 30

Graduate Colloquium

Topic: The transportation method in Concentration Inequalities.

Ying Bi | Tulane University

Abstract: The Concentration inequalities are widely used in Probability Theory, Statistical mechanics, information theory and many other fields. Among all the methods in proving such inequalities, the entropy method performs especially well when dealing with suprema of empirical processes, but often faces difficulties when deal with left tail. However, the transportation method provided by Prof Marton in the mid 1990s is more efficient for left tail. We will see the basic idea of proving inequalities based on cost function and the induction spirit in this talk with several examples at the end. Some references will also shown in the appendix for further reading.

Location: Stanley Thomas 316
Time: 5:00pm