Spring 2019
Tuesdays, 4:35–5:35 PM, JWB 335
Math 6960–001
(credit hours available!)

GSAC Home | Past Graduate Colloquia
Jan 9

## Quivers, representations, stability, and moduli spaces

Marin Petkovic

Note the special date. Classification problem is one of the biggest open problems in algebraic geometry. In some cases, this problem is equivalent to classifying quiver representations. In this talk I will give a brief introduction to quivers, their representations, and a notion of stability. If time permits, I will illustrate the connection to geometry with some examples.

Jan 16

## Poetry That Computes

China Mauck

Note the special date. Poetry and mathematics share many elements. Both require a certain amount of elegance, are sometimes formulaic, and are often riddled with hidden meanings. Some would argue that poets and mathematicians even share an overarching goal. We will consider the history of this interweaving of two seemingly opposing subjects and their surprising common ground.

Jan 22

## Graduate student forum on teaching

Kelly MacArthur

This event is an open dialogue with Kelly MacArthur for feedback, questions, and concerns about the teaching requirement for PhD students. The goal of this dialogue is to discuss things that are or are not working, and how the department might improve things going forward. This is also an opportunity to ask why the department does things in a certain way (for example, ""Why are the classes so tightly supervised/coordinated?"), assuming that Kelly knows the answer. If you're nervous to voice a particular opinion or you have a question that you don't feel comfortable asking in front of everyone, please write your comment or question on a sheet of paper and put it in Kelly's box anonymously.

Jan 29

## Periodic Trajectories in Polygonal Billiards

Matt Smith

A billiard is a classical system consisting of a point particle confined to a region with no external forces. When the region is a polygon, surprisingly little is known about the possible behaviors. In fact, whether every polygon has a periodic billiard trajectory has been open for over 200 years! Our goal is to give an elementary introduction to this problem and the methods that have been used to attack it in the past few decades.

Feb 5

## The topology of impossible shapes

Christian Klevdal

An impossible is two dimensional shape that is interpreted as the projection of a three dimensional object that cannot exist. A key example is the Penrose triangle, and other examples feature prominently in the art of MC Escher. In this talk, we will discuss what makes an impossible shape impossible, and how to precisely quantify the impossibility of a shape through a cohomology class.

Feb 14

## Let There Be Light!

George Domat

Note the different date: Thursday, February 14th. Imagine a room with mirrored walls and a single lamp. Will the entire room be illuminated by this single lamp? This question was first posed in the 1950s and has generated lots of research in dynamics and the geometry of surfaces. We will explore the history of the problem throughout the years. Along the way we will see how to rephrase the question in terms of surfaces and how the work of Maryam Mirzakhani was recently used to explore this question in rational polygons.

Feb 19

## AWM Lecture series

Utah's student chapter of the Association for Women in Mathematics is pleased to announce the Spring 2019 lecture of our speaker series. This series brings prominent female mathematicians from across the country to Utah to share their career experiences. This special talk will consist of an open discussion of career issues in mathematics. All are welcome to attend. Come with questions!

Feb 26

## How Do Bacteria Talk? Understanding Bacterial Quorum Sensing by Mathematical Modeling

Bridget Fan

Bacterial quorum sensing (QS) is a form of intercellular communication that relies on the production and detection of diffusive signaling molecules called auotinducers (AIs). Such a mechanism allows the bacteria to track their cell density in order to regulate group behavior, such as biolm formation and bioluminescence. In a number of bacterial QS systems, including V. harveyi, multiple signaling pathways are integrated into a single phosphorylation- dephosphorylation cycle (PdPC). Through mathematical modeling, we will explore how QS uses feedback loops to `decode' the integrated signals by actively changing the sensitivity in different pathways.

Mar 5

## Fun Fluid Facts

Nathan Willis

I will present several classical fluid problems that demonstrate interesting and possibly unexpected phenomena. For each example we will watch an experiment and I will provide minimal explanation and analysis to justify the observed phenomenon. Among the examples presented will be the Weissenberg Effect and the fact that Stokes flow is time reversible. No expected knowledge passed calculus and differential equations is necessary.

Mar 19

## Cold Fusion: Utah's (Academic) Scandal of the Century

Cody Fitzgerald

In 1989, Professor Stanley Pons was the Chairman of the University of Utah Chemistry Department. His research on cold fusion created one of the largest scandals in university history. This talk will trace the history of Stanley Pons, the Fleischmann-Pons experiment, and the international fallout that ensued.

Mar 26

## The Mathematics Of Dating

Rebekah Eichberg

Popular dating apps such as OkCupid, Tinder and Bumble promise to use an algorithm to help suggest people we could potentially date. Have you ever wondered how this works? Or why it doesn’t seem to work for you? In this talk, I will give an overview on the underlying algorithms of these apps. Hopefully, we will understand how the algorithms work and in particular, whether there is math involved, and whether they help us find “the one”. Please come with ideas and opinions — anecdotes are also welcome!

Apr 2

## Paradoxes of Probability and Belief

Sean Groathouse

Probability is often not intuitive, and even seemingly simple questions can become paradoxical. We will explore a few paradoxes bout probability and knowledge, hopefully bewildering ourselves a bit along the way. After we get some practice, we will attempt to resolve a paradox about probability and belief that continues to spark debate today. No background in probability is necessary.

Apr 9

## Ubiquity of Littlewood-Richardson coefficients

Qixian (Cameron) Zhao

The combinatorially defined coefficients appear in several seemingly unrelated areas in math: eigenvalues of sums of Hermitian matrices, representations of general linear group, extensions of finite abelian p-groups, and Schubert calculus. I’ll define these coefficients, explain how they appear in these areas, and discuss underlying connections (if there is any) between them.

Apr 16

## Royal Rumble Micro Talks

Eight mathematicians will have no more than five minutes to present their research as thoroughly and accessibly as possible. Topics will run the gamut from pure math, math biology, and other applied math topics. Knowledge of calculus and analytic thinking are required.

Apr 23
Organizational meeting