Talks (unless otherwise indicated) are in Davis 301 from 4–5 PM on Mondays. Refreshments begin at 3:30 on the second floor of Davis.

To make sure you get email updates, add yourself to the mathstu (if a student) or mathothers (if not) email groups. Or check the Colby Math&Stats facebook page.

You can see last semester’s schedule.

Feb. 18
John Schmitt
Middlebury
Martin Gardner’s minimum no-3-in-a-line problem

Title

Abstract

In the October 1976 Mathematical Games column of Scientific American, Martin Gardner posed the following problem: “What is the smallest number of [queens] you can put on an [n-by-n chessboard] such that no [queen] can be added without creating three in a row, a column, or a diagonal?” We’ll give a history and show how to turn this combinatorial problem into an algebraic one – one about the zeros of a polynomial – that results in a lower bound. Many opportunities for further research will be shared.

 

Feb. 25
Ben Mathes
Colby College
Pointless Spaces and Abstract Nonsense

 

Mar. 5 (Tuesday)
Christel Kesler
Colby College
Majority-Minority? Racial and Ethnic Attrition Among Multiracial and Multiethnic Children in the Contemporary United States

Title

Abstract

Recent demographic projections by the U.S. Census Bureau suggest that already around the time of next year’s Census, the majority of children in the U.S. will belong to a minority group. These projections rely on the assumption that the growing population of children whose parents are partnered across racial or ethnic lines will be classified according to the racial and ethnic categories of their minority parents – and later identify themselves within those categories. Using 2001-2017 American Community Survey (ACS) data, this paper examines the actual decisions that the parents of multiracial and multiethnic children make about how to classify their children. Racial and ethnic attrition, which occurs when parents list for their child fewer racial and ethnic categories than they list for themselves, is both widespread and socioeconomically selective. This complicates conclusions we can draw about both the relative size and relative success of various racial and ethnic groups.

 

Mar. 11 (Olin 1)
Siiri Bennett
Maine CDC
An Introduction to Public Health

Title

Abstract

What is public health, how is it different from healthcare, and how does it affect us? Dr Siiri Bennett, Maine’s State Epidemiologist, will discuss the core functions and services of public health and how the work of the Maine Center for Disease Control and Prevention (Maine CDC) plays a role in our lives.

 

Mar. 18
Abigail Taylor-Roth
Colby College
“There is no permanent place in the world for ugly mathematics”-Hardy

Title

Abstract

Over time, mathematicians have found various aspects of math to be beautiful and aesthetically pleasing. Maybe you have found math to be beautiful at times! But what really is mathematical beauty? We will talk about different perspectives on mathematical beauty and exciting questions such as “Can a definition be beautiful?” We will explore the ways that studying mathematical beauty can be an effective tool with which to examine how knowledge is produced in mathematics and our perceptions of objectivity. We will likely end up having many more questions than when we started.

 

POSTPONED – Apr. 1
Leo Livshits
Colby College
Balancing the off-diagonal corners of matrices and operators

Title

Abstract

Recently, some friends and I have been thinking about the instability of our times, and in our wishing for steadiness we started to wonder about operators that exhibited a comforting balance with respect to the middle, in a sense that neither side outweighed the other. Operators are mysterious creatures, when they inhabit infinite-dimensional realms, and so we naturally began by exploring the low-dimensional settings, which are far more familiar, and at times offer valuable insights for the explorers of the infinite. We were pleased to see that our pursuits in low dimensions did indeed yield a key to unlock the answers in all finite dimensions, but alas, the infinite-dimensional setting proved to be quite forbidding and while we secured some of the answers, the complete picture still eludes us.

What I will offer on the fool’s Monday afternoon, in this our thrice the prime year of the ascension of the 40-th emperor to the Chrysanthemum throne, is a brief introductory survey of the basic but fascinating principles from linear algebra and operator theory which were our companions throughout the journey. A learner who has partaken from the cup of MA253 or any other source of linear algebraic enlightenment will find this humble presentation pleasantly accessible and perhaps even illuminating, and while an illustrious scholar may deem it far too simple-minded, I can still hope that some of the ideas herein will please the savant, and that the afternoon will not be wasted in its entirety.

 

Cancelled – Apr. 8
Kathryn Lindsey
Boston College
Fractal kittens and complex dynamics

Title

Abstract

TBAThe Julia set of a polynomial is a fractal associated to
that polynomial.  What can these fractals look like?  For example, is
there a Julia set that looks like a cat?  Or whose Julia set spells
out your name?  The answer to both of these questions is yes.  I will
discuss how to find polynomials whose Julia sets have any desired
shape.

 

Apr. 15
Leo Livshits
Colby College
Balancing the off-diagonal corners of matrices and operators

Title

Abstract

Recently, some friends and I have been thinking about the instability of our times, and in our wishing for steadiness we started to wonder about operators that exhibited a comforting balance with respect to the middle, in a sense that neither side outweighed the other. Operators are mysterious creatures, when they inhabit infinite-dimensional realms, and so we naturally began by exploring the low-dimensional settings, which are far more familiar, and at times offer valuable insights for the explorers of the infinite. We were pleased to see that our pursuits in low dimensions did indeed yield a key to unlock the answers in all finite dimensions, but alas, the infinite-dimensional setting proved to be quite forbidding and while we secured some of the answers, the complete picture still eludes us.

What I will offer on the fool’s Monday afternoon, in this our thrice the prime year of the ascension of the 40-th emperor to the Chrysanthemum throne, is a brief introductory survey of the basic but fascinating principles from linear algebra and operator theory which were our companions throughout the journey. A learner who has partaken from the cup of MA253 or any other source of linear algebraic enlightenment will find this humble presentation pleasantly accessible and perhaps even illuminating, and while an illustrious scholar may deem it far too simple-minded, I can still hope that some of the ideas herein will please the savant, and that the afternoon will not be wasted in its entirety.

 

Apr. 22
Caitlin Lienkaemper
The Pennsylvania State University
Combinatorics, topology, and geometry from neuroscience

Title

Abstract

How did you get here? You got some help from place cells, neurons, which act as sensors for their receptive fields, which are (approximately) convex subsets of the environment. Given neural data, how can we tell whether it comes from place cells?

More mathematically: given a combinatorial neural code (a collection of subsets of {1,2,…,n}), how can we tell whether it is the intersection pattern of a collection of convex open subsets of $\mathbb R^d$? We introduce ideas from topology which help us answer this question, but show that they cannot give us a complete answer. We are left with more questions than answers, and thus end with some open problems in geometry.

 

May 2
Math/Stats @ Colby Liberal Arts Symposium
Lots of Talks!

Title

Abstract

Visit colby.edu/clas for details!