Colloquia

Current Talks

30 minutes before the talk refreshments will be served in MSPB 350. 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, February 23, 2023 at 3:30 p.m. in MSPB 370 Hossein Moradi, South Dakota State University

TBA

Abstract: TBA

Thursday, March 2, 2023 at 3:30 p.m. in MSPB 370 Norou Diawara, Old Dominion University

Copula-Based Bivariate Zero-Inflated 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 integer-valued time series models is constructed via copula theory. Each time series follows Markov chains with the serial dependence is captured using copula-based transition probabilities with the Poisson and the zero-inflated Poisson (ZIP) margins. The copula theory is also used again to capture the dependence between the two series using either the bivariate Gaussian or t-copula 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, March 30, 2023 at 3:30 p.m. in MSPB 370 Bülent Tosun, University of Alabama

TBA

Abstract: TBA

Previous Talks

 

Date Speaker Talk
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 NSF-funded project scoping the development of an Open-Source 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 real-world 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 torus-equivariant 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 Liouville-like Quantum Gravity Action

Abstract: In this paper, we present a new stochastic differential game-theoretic model of optimizing strategic behavior associated with a soccer player under the presence of stochastic goal dynamics by using a Feynman-type path integral approach, where the action of a player is on a √8/3-Liouville 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 low-dimensional topology; every 3- and 4-manifold can be represented by a weighted link. When studying 3-manifolds, one considers isotopy as the relevant equivalence relation whereas when studying 4-manifolds, 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 multi-Seifert 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 n-solvable equivalence. We will show that most links are 0- and 0.5-solvably equivalent but that for larger n, that there are links not n-solvably 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 data-based intervals that are meant to capture a pre-specified large proportion of the population values of a clinical marker or analyte in a healthy population. They can be one-sided or two-sided, 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 component-wise 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 non-parametric 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

Cost-Effectiveness Analysis: A Statistical Overview

Abstract: Identifying treatments or interventions that are cost-effective (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 cost-effectiveness that are informative, intuitive and simple to explain have been suggested in the literature. Popular and widely used measures include the incremental cost-effectiveness 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 "willingness-to-pay" amount. In the talk, I will provide a fairly non-technical review of the area of cost-effectiveness analysis, and its importance in health policy decision making. Some recently introduced cost-effectiveness 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.

For colloquium talks from previous years click here