Colloquia
Current Talks
30 minutes before the talk refreshments will be served in MSPB 335 (Library). If the talk is on Zoom, then the link for both the virtual "refreshments" and the talk is https://southalabama.zoom.us/j/5059668430
Join us to meet the speaker and the Mathematics & Statistics Faculty here at South!
Date  Speaker  Talk 

Thursday, September 21, 2023 at 3:30 p.m. in MSPB 370 
Jeffrey Mudrock, University of South Alabama 
Title: Let’s Color! Abstract: Coloring graphs is a topic that was introduced in the 1850s. Over the past 170 years, the study of graph coloring has led to the development and discovery of some rich and beautiful mathematics. Also, the applications of graph coloring are vast, and applications can be found in scheduling, problems on social networks, design of seating plans, the assignment of frequencies to radio stations, the equitable distribution of resources, and much more! Another intriguing property of graph coloring is that one does not need a lot of mathematical background to understand many graph coloring questions that remain a mystery to the human race today. Since graph coloring is a relatively young research topic, it is also possible to make progress on some graph coloring questions through elementary ideas such as: extremal, inductive, and algorithmic techniques. This makes graph coloring an ideal playground for both undergraduate and graduate students. In this talk I will introduce graph coloring and discuss some of its historical development and famous questions. Then, I will introduce a wellknown generalization of classical graph coloring called list coloring which also has abundant applications. The talk will end with some results that were recently obtained on list coloring as part of an undergraduate research project with students: Kennedy Cano, Emily Gutknecht, Gautham Kappaganthula, Ezekiel Thornburgh, and George Miller. 
Thursday, September 28, 2023 at 3:30p.m. in MSPB 370 
Steven Clontz, University of South Alabama 
Title: NonHausdorff T₁ Properties and Sociotechnical Infrastructure for Mathematics Research Abstract: Several weakenings of the T₂ property for topological spaces, including kHausdorff, KC, weakly Hausdorff, semiHausdorff, RC, and US, have been studied in the literature. Here we investigate how these properties do or do not relate to one another, and in doing so, illustrate and evaluate the role of technology in modern mathematics research. 
Thursday, October 5, 2023 at 3:30 p.m. in MSPB 370 
Martha Makowski, University of Alabama 
Title: Unpacking Gendered Differences in Approaches to Mathematical Problems: Implications and Potential Explanations Abstract: Despite progress toward gender equity in past decades, gender differences in math problemsolving performance and career outcomes remain, with women pursuing careers in science, technology, engineering, and math less often than men. This talk will summarize extant theories about what contributes to gendered participation differences in mathematics, with a focus on the role socialization and environment may play. Within this, I introduce evidence that the strategies used on basic computation problems relate to problem solving performance on more complex mathematical tasks and introduce the construct of “Bold Problem Solving”, an approach to mathematics that involves risktaking and inventiveness. A throughline of this work is that gender differences in mathematical performance are related to gendered differences in strategy use and bold problem solving, suggesting that girls and women learn how to do mathematics differently than their male peers. Implications for future work and teacher professional development are discussed. 
Tuesday (!), October 10, 2023 at 3:30 p.m. in MSPB 370 
Scott Carter, University of South Alabama 
Title: Playing With the Binary Icosahedral Group Abstract: For a little while, I have been trying to understand several things: (1) The 5fold branched cover of the 3sphere that is branched along the trefoil knot, (2) the five twist spin of the trefoil, (3) the group of (2by2) matrices that have entries in the integers mod 5, (4) the Poincare homology sphere, (5) the binary icosahedral group. The cognoscenti will observe that these are all related topics. In the talk, I will sketch why they are related and I'll preview the things that I have found out. My purpose is to educate myself and others because I feel that at the most basic level of instruction not enough is said on these examples that are key to the understanding of low dimensional topology. In particular, students are invited. I'll do my best to present things in an elementary fashion. 
Thursday, October 19, 2023 at 3:30 p.m. in MSPB 370 
Siddhi Pathak, Chennai Mathematical Institute 
Title: TBC Abstract: TBC

Thursday, November 9, 2023 at 3:30 p.m. in MSPB 370 
Jonas Hartwig, Iowa State University 
Title: TBC Abstract: TBC 
Thursday, November 16, 2023 at 3:30 p.m. in MSPB 370 
Olivia Beckwith, Tulane University 
Title: TBC Abstract: TBC

Thursday, January 25, 2024 at 3:30 p.m. in MSPB 370 
Mikhail Khovanov, Johns Hopkins University / Columbia University 
Title: TBC Abstract: TBC

Previous Talks
Date  Speaker  Talk 

Tuesday, April 25, 2023 at 3:30 p.m. in MSPB 370  Changrui Liu, University of Kentucky 
Hypothesis Testing on WilcoxonMannWhitney Effect for Clustered Data under Informative Cluster Size Abstract: Under the general nonparametric settings where data are clustered and the size of each cluster is informative, we address the issue of comparing two groups of observations in terms of the WilcoxonMannWhitney effect (also known as the nonparametric relative effect). With the help of a technique called withincluster resampling (WCR), several rankbased tests are proposed with the goal to assess whether the given two groups are tendentiously equivalent to each other. Computationally, results from simulation data have shown evidence that our tests maintain a reasonably high power and a correct size compared to existing methods in the literature. Furthermore, we provide interval estimates of the nonparametric relative effect by inverting our tests. These findings contribute to the development of more efficient and accurate methods for comparing the stochastic equality of two groups in the setting of clustered data under informative cluster size. 
Thursday, April 20, 2023  Akash Roy, Duke University 
Nonparametric Rank Based Methodology in Cluster Data Analysis Abstract: Statistical comparison of two independent groups is one of the most frequently occurring inference problems in scientific research. Most of the existing methods available in the literature are not applicable when measurements are taken with dependent replicates. In all these scenarios the replicates should neither be assumed to be independent nor come from different subjects. Furthermore, using a summary measure of the replicates would decrease the precision of the effect estimates. So, a solution is proposed for these two sample problems with correlated replicates. Furthermore, major attention will be given to the accuracy of the tests in terms of controlling the nominal TypeI error level as well as their powers when sample sizes are rather small. 
Tuesday, April 4, 2023  Sarah Allred, Vanderbilt University 
Unavoidable Induced Subgraphs of 2Connected Graphs Abstract: Ramsey proved that for every positive integer r, every sufficiently large graph contains as an induced subgraph either a complete graph on r vertices or an independent set with r vertices. It is well known that every sufficiently large, connected graph contains an induced subgraph isomorphic to one of a large complete graph, a large star, and a long path. We prove an analogous result for 2connected graphs. Similarly, for infinite graphs, every infinite connected graph contains an induced subgraph isomorphic to one of the following: an infinite complete graph, an infinite star, and a ray. We also prove an analogous result for infinite 2connected graphs. 
Thursday, March 30, 2023  Hossain Md. Sadhawa, Texas Tech University 
TwoInput and TwoOutput Predictive Model for Multifunctional Materials with Hysteresis and Thermodynamic Compatibility Abstract: Multifunctional materials have tremendous potential for engineering applications as they are able to convert mechanical to electromagnetic energy and viceversa. One of the features of this class of materials is that they show significant hysteresis, which needs to be modeled correctly in order to maximize their application potential. A method of modeling multifunctional materials that exhibit the phenomenon of hysteresis and is compatible with the laws of thermodynamics was developed recently. The model is based on the Preisach hysteresis operator and its storage function and may be interpreted as a twoinput, twooutput neural net with elementary hysteresis operators as the neurons. The difficulty is that the parameters in the model appear in a nonlinear fashion, and there are several constraints that must be satisfied by the parameters for thermodynamic compatibility. In this research, we present a novel methodology that uses the rateindependent memory evolution properties of the Preisach operator to split the parameter estimation problem into three numerically wellconditioned, linear least squares problems with constraints. The alternative direction method of multipliers(ADMM) algorithm and accelerated proximal gradient method are used to compute the Preisach weights. Numerical results are presented over data collected from experiments on a Galfenol and a TerfenolD sample. We show that the model is able to fit not only experimental data for strain and magnetization over a wide range of magnetic fields and stress but also able to predict the response for stress and magnetic fields not used in the parameter estimation. 
Thursday, March 30, 2023 
Bülent Tosun, The University of Alabama 
On Embedding Problems for 3Manifolds in 4Space Abstract: The problem of embedding one manifold into another has a long, rich history, and proved to be tremendously important for development of geometric topology since the 1950s. In this talk I will focus on the 3manifold embedding problem(s) in 4dimensional Euclidean space R^{4}. Given a closed, orientable 3manifold Y, it is of great interest but often a difficult problem to determine whether Y may be smoothly embedded in R^{4}. This is the case even for integer homology spheres (where usual obstructions coming from homology disappear), and restricting to special classes such as Seifert manifolds, the problem is open in general, with positive answers for some such manifolds and negative answers in other cases. On the other hand, under additional geometric considerations coming from symplectic geometry (such as hypersurfaces of contact type in R^{4}) and complex geometry (such as the boundaries of holomorphically or rationally or polynomially convex domains in complex Euclidean space C^{2}), the problems become tractable and in certain cases a uniform answer is possible. For example, recent work shows for Brieskorn homology spheres: no such 3manifold admits an embedding as a hypersurface of contact type in R^{4}. This implies restrictions on the topology of rationally and polynomially convex domains in C^{2}. In this talk I will provide further context and motivations for these results, and give some details of the proof. 
Tuesday, March 28, 2023  Yi Fan, University of Florida 
Online Monitoring of Image Sequences Abstract: To monitor the Earth’s surface, the satellite of the NASA Landsat program provides us image sequences of any region on the Earth constantly over time. Gradual loss of water resource in the Salton Sea has got much attention from researchers for its damage to the local environment and ecosystems. To monitor the water resource of the lake, researchers usually obtain certain water resource indices manually from databases such as the satellite images of the region. We developed a new method to monitor the area of the Salton Sea automatically. By this method, the lake boundary is first segmented from each satellite image by an image segmentation procedure, and then its area is computed by a numerical algorithm. The sequence of lake areas computed from satellite images taken at different time points is then monitored by a control chart from the statistical process control literature. Because the lake area changes gradually over time, a new control chart designed for detecting process mean drifts is also proposed. 
Thursday, March 23, 2023  Benjamin Hutz, Saint Louis University 
Automorphism Groups for Arithmetic Dynamical Systems Abstract: Algebraic dynamics is the study of iteration of polynomial or rational functions. This talk focuses on dynamical systems with nontrivial automorphisms. Under the action of conjugation by fractional linear transformations, we can form a moduli space of dynamical systems of a certain degree. Certain elements in these moduli spaces have nontrivial automorphisms. This is analogous to the elliptic curves with complex multiplication in the moduli space of elliptic curves. These special maps have connections to many problems in arithmetic dynamics. I focus on two problems in this talk: identifying the locus of maps with nontrivial automorphisms and the realizability of subgroups of the projective linear group as automorphism groups. As time allows, I will use this automorphism locus to motivate a future project: the creation of a database of dynamical systems. 
Tuesday, March 21, 2023  Kevin Grace, Vanderbilt University 
Dyadic Matroids with Spanning Cliques Abstract: The Matroid Minors Project of Geelen, Gerards, and Whittle describes the structure of minorclosed classes of matroids representable by a matrix over a fixed finite field. To use these results to study specific classes, it is important to study the matroids in the class containing spanning cliques. A spanning clique of a matroid M is a completegraphic restriction of M with the same rank as M. In this talk, we will describe the structure of dyadic matroids with spanning cliques. The dyadic matroids are those matroids that can be represented by a real matrix each of whose nonzero subdeterminants is a power of 2, up to a sign. A subclass of the dyadic matroids is the signedgraphic matroids. In the class of signedgraphic matroids, the entries of the matrix are determined by a signed graph. Our result is that dyadic matroids with spanning cliques are signedgraphic matroids and a few exceptional cases. The main results in this talk will come from joint work with Ben Clark, James Oxley, and Stefan van Zwam. This talk will include a brief introduction to matroids. 
Thursday, March 16, 2023  Fadekemi Janet Osaye, Alabama State University 
Modeling COVID19 Pandemic using Graph Theory Abstract: The coronavirus has affected many countries and taken the lives of several thousands of people since its outbreak in 2019. The spread (pandemic) pattern of this virus can be analyzed from graph theory perspective where the COVID19 can be represented as a graph with each vertex representing an individual at any particular stage of infection (asymptomatic, presymptomatic, symptomatic, or vaccinated), and an edge indicating the transmission from person to person. This project considers the neighborhood prevalence of each individual, i.e., proportion of each individual's contacts who are either exposed or infected, and describe parameters for a threshold value R < 1 and R > 1 on the spread of the pandemic. This threshold value is similar to the reproduction number of the pandemic. 
Tuesday, March 14, 2023  Jeffrey Mudrock, College of Lake County 
On Chromatic Polynomials, List Color Functions, and DP Color Functions Abstract: Counting proper colorings of graphs is a fundamental topic in enumerative combinatorics that has been extensively studied since the early 20th century. Specifically, the chromatic polynomial of a graph G, denoted P(G,m), is equal to the number of proper mcolorings of G. List coloring is a widely studied generalization of classical coloring that was introduced in the 1970s, and DPcoloring is a generalization of list coloring that has received considerable attention since its introduction in 2015. In this talk we present an overview of both a list coloring analogue and DPcoloring analogue of the chromatic polynomial which are called the list color function and DP color function respectively. For a given graph G we will be primarily interested in comparing the list color function and DP color function of G to P(G,m). Specifically, we will present results and open questions related to the following questions. Does the list color function (resp. DP color function) of G eventually equal P(G,m) for sufficiently large m? When the answer to this question is yes, we will also ask: What is the smallest m at which the list color function (resp. DP color function) of G is nonzero, equals P(G,m), and stays equal to the chromatic polynomial of G for all integers greater than m? The results we present have proofs that utilize a diverse array of techniques from algebraic, extremal, and probabilistic combinatorics. This talk will include joint works with Vui Bui, Samantha Dahlberg, Charlie Halberg, Hemanshu Kaul, Akash Kumar, Andrew Liu, Michael Maxfield, Patrick Rewers, Paul Shin, Seth Thomason, and Khue To. 
Thursday, March 2, 2023  Norou Diawara, Old Dominion University 
CopulaBased Bivariate ZeroInflated Poisson Time Series Models Abstract: Count time series data are found in multiple applications such as environmental science, biostatistics, economics, public health, and finance. Such time series counts come with inflation and in a bivariate form that captures not only serial dependence within each time series but also interdependence between the two series. To accurately study such data, one needs to account for the two types of dependence that emerge from the observed data, and the inflation. A class of bivariate integervalued time series models is constructed via copula theory. Each time series follows Markov chains with the serial dependence is captured using copulabased transition probabilities with the Poisson and the zeroinflated Poisson (ZIP) margins. The copula theory is also used again to capture the dependence between the two series using either the bivariate Gaussian or tcopula functions. Likelihood based inference is used to estimate the model parameters with the bivariate integrals of the Gaussian or t copula functions being evaluated using standard randomized Monte Carlo methods. To evaluate the proposed class of models, a comprehensive simulated study is conducted capturing both positive and negative cross correlations. Then, two real life datasets are analyzed assuming the Poisson and the ZIP marginals, respectively. The results show the promises of the proposed class of models. Extensions to other class of count time series will be presented. 
Thursday, January 26, 2023  Steven Clontz, University of South Alabama
This talk is aimed at a general audience! 
Open Educational Resources in Mathematics Education Abstract: PROSE (https://prose.runestone.academy) is the presenter's NSFfunded project scoping the development of an OpenSource Ecosystem surrounding software products that support the authoring and publishing of accessible Open Educational Resources in STEM. This presentation will overview the free technologies and educational resources involved in this ecosystem, and how they may be used to enhance mathematics instruction at the university and high school levels. This talk is aimed at current and future mathematics instructors, as well as undergraduate and graduate students who are considering industry careers related to software engineering. 
Thursday, January 12, 2023  Julianna Tymoczko, Smith College
This talk is directed especially toward undergraduate and graduate students in mathematics or related subjects. 
An Introduction to Generalized Splines Abstract: Splines are a fundamental tool in applied mathematics and analysis, classically described as piecewise polynomials on a combinatorial decomposition of a geometric object (a triangulation of a region in the plane, say) that agree up to a specified differentiability wherever two faces of the decomposition intersect. Generalized splines extend this idea algebraically and combinatorially: instead of certain classes of geometric objects, we start with an arbitrary combinatorial graph; instead of labeling faces with polynomials, we label vertices with elements of an arbitrary ring; and instead of applying degree and differentiability constraints, we require that the difference between ring elements associated to adjacent vertices is in a fixed ideal labeling the edge. Billera showed that generalized splines can be used to recover classical splines in most cases of realworld interest. Independently, a long and deep line of research into localization techniques in toric topology culminated in a result of Goresky, Kottwitz, and MacPherson showing that generalized splines can also be used to compute the torusequivariant cohomology of suitable algebraic varieties. In this talk, we describe generalized splines, how they extend classical splines (as well as ideas from other fields, from number theory to algebraic topology), and give some results on a longstanding open problem about the dimension of the space of splines on triangulations of the plane. 
Thursday, December 1, 2022  Paramahansa Pramanik, University of South Alabama
This talk is directed especially toward undergraduate and graduate students in mathematics or related subjects. 
Scoring a Goal Optimally in a Soccer Game under Liouvillelike Quantum Gravity Action Abstract: In this paper, we present a new stochastic differential gametheoretic model of optimizing strategic behavior associated with a soccer player under the presence of stochastic goal dynamics by using a Feynmantype path integral approach, where the action of a player is on a √8/3Liouville quantum gravity surface. Strategies to attack the oppositions have been used as control variables with extremes like excessive defensive and offensive strategies. As in a competitive tournament, all possible standard strategies to score goals are known to the opposition team, a player's action is stochastic, and they would have some comparative advantages to score goals. Furthermore, conditions like uncertainties due to rain, dribbling, and passing skills of a player, time of the game, home crowd advantages, and asymmetric information of action profiles are considered to determine the optimal strategy. 
Tuesday, November 29, 2022 
Brian Mooneyham, VP Analytics, Decision Support and Data Visualization at a Large Financial Institution 
How Being a Math and Data Nerd Can Make You $uccessful! Abstract: Brian will talk about his journey from graduating from USA with a degree in Mathematics to becoming a featured expert in the data and analytics world. He’ll share how his education prepared him to get jobs and important skills that he picked up along the way to allow him to keep advancing during the data explosion. If time allows, Brian will share how companies are currently using data to understand their businesses and to make data driven decisions as well as what’s next. 
Thursday, November 10, 2022  Shelly Harvey, Rice University
Students in mathematics and related subjects are encouraged to attend. 
Linking in 3.5 Dimensions Abstract: Knots are circles embedded into Euclidean space and links are disjoint knots with multiple components. The classification of links is essential for understanding the fundamental objects in lowdimensional topology; every 3 and 4manifold can be represented by a weighted link. When studying 3manifolds, one considers isotopy as the relevant equivalence relation whereas when studying 4manifolds, the relevant condition becomes knot and link concordance. In some sense, the nicest class of links are the ones called boundary links; like a knot, they bound disjointly embedded orientable surfaces in Euclidean space, called a multiSeifert surface. The strategy to understand link concordance, starting with Levine in the 60's, was to first understand link concordance for boundary links and then to try to relate other links to boundary links. However, this point of view was foiled in the 90's when Tim Cochran and Kent Orr showed that there were links (with all known obstructions, i.e., Milnor's invariants, vanishing) that were not concordant to any boundary link. In this work, Chris Davis, Jung Hwan Park, and I consider weaker equivalence relations on links filtering the notion of concordance, called nsolvable equivalence. We will show that most links are 0 and 0.5solvably equivalent but that for larger n, that there are links not nsolvably equivalent to any boundary link (thus cannot be concordant to a boundary link). I won't assume any knowledge of knot or link theory in this talk and there will be a lot of pictures! This is joint work with C. Davis and J.H. Park. 
Thursday, November 3, 2022  Scott Larson, University of Georgia
Students in mathematics or related subjects are encouraged to attend. 
Seeking Better Perspectives of Symmetry Abstract: To understand a problem in a given setting, it is often helpful to describe all symmetries. One technique to perceive symmetry is to imagine reversible actions according to a set of rules. For example, you can reflect a butterfly across a vertical axis and get the same picture. In this example, there is only one simple rule, but in general describing the (infinitely many) rules is a difficult problem that often leads to deep solutions and beautiful pictures. I will describe some symmetries important for physics and algebraic geometry, and indicate various perspectives developed over time to exploit extra structure. The talk will conclude with a computer calculation using some of the deepest known theory in algebraic geometry, combinatorics, and representation theory to show how certain smooth spaces need to collapse, while preserving symmetry, to describe singular spaces important for Lie theory. 
Thursday, October 27, 2022  Thomas Mathew, University of Maryland Baltimore County (UMBC) 
Reference Intervals and Regions in Laboratory Medicine Abstract: Reference intervals are databased intervals that are meant to capture a prespecified large proportion of the population values of a clinical marker or analyte in a healthy population. They can be onesided or twosided, and they are widely used in the interpretation of results of biochemical and physiological tests of patients. A population reference range is typically expected to include 95% of the population distribution, and reference limits are often taken to be the 2.5th and 97.5th percentiles of the distribution, which is especially meaningful if normality is appropriate. Usually the reference range is constructed based on a random sample and simply estimating the percentiles is clearly not satisfactory. This calls for the use of appropriate criteria for estimating the reference range from a random sample. When there are multiple biochemical analytes measured from each subject, a multivariate reference region is needed. Traditionally, under multivariate normality, reference regions have been constructed as ellipsoidal regions. This approach suffers from a major drawback: it cannot detect componentwise extreme observations. Thus rectangular reference regions need to be constructed based on appropriate criteria. The talk will review univariate reference intervals and multivariate reference regions, and the criteria that can be used in their construction. Both parametric and nonparametric scenarios will be addressed, and laboratory medicine examples will be used for illustration. 
Wednesday, October 26, 2022
This talk is aimed at a general audience! 
Thomas Mathew, University of Maryland Baltimore County (UMBC)
Seventh Satya Mishra Memorial Lecture 
CostEffectiveness Analysis: A Statistical Overview Abstract: Identifying treatments or interventions that are costeffective (more effective at a reasonable cost) is clearly important in health policy decision making, especially in the allocation of health care resources. Various measures of costeffectiveness that are informative, intuitive and simple to explain have been suggested in the literature. Popular and widely used measures include the incremental costeffectiveness ratio (ICER), defined as the ratio between the difference of average costs and the difference of average effectiveness in two populations receiving two treatments. The ICER is interpreted as the additional cost per unit of effectiveness gained. Yet another measure proposed is the incremental net benefit (INB), which is the difference between the incremental cost and the incremental effectiveness after multiplying the latter with a "willingnesstopay" amount. In the talk, I will provide a fairly nontechnical review of the area of costeffectiveness analysis, and its importance in health policy decision making. Some recently introduced costeffectiveness measures will be discussed and examples will be given. 
Thursday, September 29, 2022  Armin Straub, University of South Alabama
This talk is directed especially toward undergraduate and graduate students in mathematics or related subjects. 
Gaussian Binomial Coefficients with Negative Arguments Abstract: In the early 90's, Loeb showed that a natural extension of the usual binomial coefficient to negative (integer) entries continues to satisfy many of the fundamental properties. In particular, he gave a uniform binomial theorem as well as a combinatorial interpretation in terms of choosing subsets of sets with a negative number of elements. We tell this remarkably little known story and show that all of it can be extended to the case of Gaussian binomial coefficients. This talk is based on joint work with Sam Formichella, a former undergraduate student at South. 