# News

## Dan Solomon Ph.D Defense

A New Compactification for Celestial Mechanics.

Date: 11/3/2017
Time: 3:30PM-5:00PM
Place: 315 Armstrong Hall

All are welcome.

Date, Location:
2017-11-03

## Math Prof, Neutron Stars

For the first time, scientists have directly detected gravitational waves—ripples in space and time—from the spectacular collision of two neutron stars. Light from the collision was also observed by telescopes, marking the first time that a cosmic event has been viewed in both gravitational waves and light.

Date, Location:
2017-10-31

## Tim McCarty Prospectus

How Experts Conceptualize Differentials

Abstract: The differential is a symbol found in many mathematical contexts, including notations for differentiation and integration. But even though such notations are common, there can be many interpretations of the purposes or roles of the differentials in these notations. I wished to interview mathematicians and physicists to see how they interpreted differentials in a variety of settings and conducted two small studies to that end. I shall begin my talk by discussing a brief history of differential notation, the conceptualizations of the differential suggested by RUME and PER literature, and the idea of concept image (Tall & Vinner, 1981), which has shaped my research. I shall then present the results of my studies, which show that not only is there no formal concept definition of the differential evoked by all subjects, but there is also the suggestion that mathematicians and physicists view differentials contrarily.

Date: 10/16/2017
Time: 4:00PM-5:30PM
Place: 203 Armstrong Hall

Date, Location:
2017-10-16

## Kristen Murphy Prospectus

Abstract: Spatial reasoning is required for many topics in undergraduate mathematics; graphing, curve sketching, transformations of functions, manipulation of objects in 3D, etc. Many topics covered in calculus require the student to use some sort of spatial skill to make informed decisions related to the problem at hand. However, unlike topics such as algebra and trigonometry, there are few programs that test students on their spatial reasoning skills before entering a course and then provide remediation if the student is lacking in that area. Some engineering programs do such testing and provide remediation, but no literature can be found on mathematics programs doing this. This study will employ haptic technology, computer-based technology that provides touch feedback, in order to determine if students who score low on a spatial skills test can be helped to refresh or acquire the skills they lack that will be necessary for later success in the calculus courses.

Date: 9/6/2017
Time: 4:00PM-5:30PM
Place: 119 Armstrong Hall

Date, Location:
2017-09-06

## Student Receives $5000 Actuarial Scholarship Congratulations to Maleesha Ebanks! She received Milliman Actuarial scholarship$5000, which is targeted toward minority students that are underrepresented in the actuarial and professional services fields. She passed the first actuarial exam in July 2016 after taking Math 363 and attending the additional weekly practice session hosted by Actuarial Student Club. She said this scholarship has given her more motivation for passing next actuarial exam in December 2017. She is currently taking Math 364, which prepares her to take the second actuarial exam FM.

Date, Location:
2017-08-18

Algorithms for Computing the Inverse of a Curl

Abstract: In order to transform data from a numerical simulation of binary black holes in which only the magnetic field B is computed, to another simulation in which only the vector potential A is computed, ∇ × A = B must be solved to generate a vector potential from the known magnetic field vector. We implement multiple methods for solving this equation based on finite difference numerical representations of the equation. One method of solving this equation directly is to solve the problem sequentially point-by-point, using the solution at previous points as constraints.

Two other methods of solving this problem focus on taking the curl of both sides of the equation and solve the resulting Poisson's equation. The first of these methods is to set up a large but very sparse matrix and solve globally using Gaussian Elimination. The second of these methods is perform a multigrid solve by setting up the problem on grids of multiple resolutions and solving on each level using an iterative technique.

Of the two Poisson's equation methods the multigrid solver is determined through testing to have superior computational scaling for very large magnetic fields to the global solver. It also holds the advantage over the direct point-by-point method of being able to easily incorporate adaptive mesh refinement which is needed for solving the problem on the incredibly large magnetic fields used by the simulations. This leads to the conclusion that the multigrid method should be the primary focus for testing and implementation.

Date: 7/12/2017
Time: 3:30PM-4:30PM
Place: 415 Hodges

All are welcome.

Date, Location:
2017-07-12

## Jian Cheng Defense

Integer Flows and Circuit Covers of Signed Graphs

Abstract: View

Date: 7/7/2017
Time: 10:00AM-12:00PM
Place: 207 Armstrong Hall

All are welcome.

Date, Location:
2017-07-07

On the Matroid Intersection Conjecture

Abstract: In this dissertation, we investigate the Matroid Intersection Conjecture for pairs of matroids on the same ground set, proposed by Nash-Williams in 1990. Originally, the conjecture was stated for finitary matroids only, but we consider it for general matroids and introduce new approaches to attack the conjecture.

The first approach is to consider the situation when it is possible to make a finite modification to the matroids after which the pair satisfies the conjecture. In such a situation we say that the pair has the “Almost Intersection Property”. We prove that any pair of matroids with the Almost Intersection Property must satisfy the Matroid Intersection Conjecture. Using this result we prove that the Matroid Intersection Conjecture is true in the case when one of the matroids has finite rank and also in the case when one of the matroids is a patchwork matroid.

Our second new approach is inspired by the proof of the general version of König’s Theorem for bipartite graphs. That result implies that the Matroid Intersection Conjecture is true for pairs of partition matroids. We develop some new techniques that generalize the "critical set" approach used in the proof of the countable version of König’s Theorem. Our results enable us to prove that the Matroid Intersection Conjecture is true for a pair of singular matroids on a set that is infinitely countable. A matroid is singular when it is a direct sum of matroids such that each term of the sum is a uniform matroid either of rank one or of co-rank one.

Date: 6/26/2017
Time: 2:00PM-4:00PM
Place: 207 Armstrong Hall

All are welcome.

Date, Location:
2017-06-26

## Jaxon Lee Capstone

Analytic Approaches to Common Means and their Inequalities

Abstract: Means are measurements of centrality, commonly used in science, engineering, statistics, and mathematics. There is a plethora of means and they measure centrality differently as to obtain the most pertinent information to the question at hand. We will discuss a specific subclass of means called Pythagorean means, which include the arithmetic, geometric, and harmonic means. We will also discuss the root mean squared, as these four means are the most common means to run into in science, engineering, and statistics applications. Lastly, we will show how the value of each of the means is related to one another through the inequality relationship between them.

Date: 6/21/2017
Time: 4:00PM-5:00PM
Place: 123 Armstrong Hall

All are welcome.

Date, Location:
2017-06-21