# Difference between revisions of "Cookie seminar"

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Title: an unsolved graph isomorphism problem from plane geometry | Title: an unsolved graph isomorphism problem from plane geometry | ||

− | Abstract: A geometric 4-configuration is a collection of $n$ lines and $n$ points in | + | Abstract: A geometric 4-configuration is a collection of <math>$n$</math> lines and $n$ points in |

the Euclidean plane with the property that each of the lines passes through exactly four | the Euclidean plane with the property that each of the lines passes through exactly four | ||

of the points, and each of the points lies on exactly four of the lines. No | of the points, and each of the points lies on exactly four of the lines. No | ||

Line 18: | Line 18: | ||

the construction and nomenclature of the celestial configurations, I'll describe an open | the construction and nomenclature of the celestial configurations, I'll describe an open | ||

problem regarding their graph-theoretical properties. | problem regarding their graph-theoretical properties. | ||

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==Monday, February 4, Paul Tveite== | ==Monday, February 4, Paul Tveite== |

## Latest revision as of 12:24, 26 September 2014

**General Information**: Cookie seminar will take place on Mondays at 3:30 in the 9th floor lounge area. Talks should be of interest to the general math community, and generally will not run longer then 20 minutes. Everyone is welcome to talk, please just sign up on this page. Alternatively I will also sign interested people up at the seminar itself. As one would expect from the title there will generally be cookies provided, although the snack may vary from week to week.

To sign up please provide your name and a title. Abstracts are welcome but optional.

## Contents

## Spring 2013

## Monday, January 28, Will Mitchell

Title: an unsolved graph isomorphism problem from plane geometry

Abstract: A geometric 4-configuration is a collection of lines and $n$ points in the Euclidean plane with the property that each of the lines passes through exactly four of the points, and each of the points lies on exactly four of the lines. No illustration of a 4-configuration appeared in print until 1980. The so-called "celestial configurations" are a well-behaved family of these objects. After discussing the construction and nomenclature of the celestial configurations, I'll describe an open problem regarding their graph-theoretical properties.

## Monday, February 4, Paul Tveite

Math and redistricting: Redrawing of congressional districts in the US is a political process with interesting results. It's also an interesting mathematical problem. I'll introduce a couple measures of irregularity of districts and a couple algorithms for objectively drawing district lines.

## Monday, February 18, Diane Holcomb

Title: The mathematics of apportionment

Abstract: Every year the United States conducts a census and then gives out or apportions seats in the House of Representatives to each of the states according to its population, unfortunately the constitution doesn't provide much guidance on how exactly to do this. I'll go over a bit of the history of how the US has apportioned the seats in the House and some of the math behind the different methods.

## Monday, March 11, David Diamondstone

Title: "pi" in different metrics

Abstract: In honor of pi day, we will explore the other values pi might have had, if we lived with a non-Euclidean metric. Examples include the universe of Carl Sagan's *Contact*, surfaces of constant curvature, and metrics which arise from norms on **R**^{2}.