# Colloquia

## Deborah Chun

Matroids and wilder things: Polymatroids and Delta-matroids

Abstract: Matroids will be introduced in this talk. I will give an example of a result for general matroids, which has interesting corollaries in more specialized classes of structures, like graphs. I will also discuss two generalizations of matroids. In polymatroids, I will give a conjecture from Vertigan, that, if true, has an important corollary in matroid theory. That is, it gives us Rota's conjecture. In delta-matroids, I will present a splitter theorem.

Date: 4/13/2017

Time: 4:00PM-5:00PM

Place: 315 Armstrong Hall

All are welcome.

## Hiroki Matsui

Thick subcategories of modules and characterizations of local rings

Abstract: View

Date: 4/12/2017

Time: 4:00PM-5:00PM

Place: 313 Armstrong Hall

All are welcome.

## C.F. Jeff Wu

From real world problems to esoteric research: examples and personal experience

Abstract: Young (and some not-so-young) researchers often wonder how to extract good research ideas and develop useful methodologies from solving real world problems. The path is rarely straightforward and its success depends on the circumstances, tenacity and luck. I will use three examples to illustrate how I trod the path. The first involved an attempt to find optimal growth conditions for nano structures. It led to the development of a new method “sequential minimum energy design (smed)”, which exploits an analogy to potential energy of charged particles. After a few years of frustrated efforts and relentless pursuit, we realized that smed is more suitable for generating samples adaptively to mimic an arbitrary distribution rather than for optimization. The main objective of the second example was to build an efficient statistical emulator based on finite element simulation results with two mesh densities in cast foundry operations. It eventually led to the development of a class of nonstationary Gaussian process models that can be used to connect simulation data of different precisions and speeds. The third example is about sequential design that works well for small samples in sensitivity testing. I will describe three major papers in a span of 30 years and how each paper had one new idea that inspired the next paper. In each example, the developed methodology has broader applications beyond the original problem. I will explain the thought process in each example. Finally, I will share some secrets about a “path to innovation”.This talk will have many illustrative examples, and should be accessible to graduate students.

Date: 4/06/2017

Time: 3:30PM-4:30PM

Place: Evansdale Crossing 414

All are welcome.

## Hiroki Matsui

Thick subcategories of modules and characterizations of local rings

Abstract: View Hiroki Matsui Abstract

Date: 4/05/2017

Time: 4:00PM-5:00PM

Place: 315 Armstrong Hall

All are welcome.

## RUME Seminar

Improving Student Understanding of Multivariable Calculus Concepts with CalcPlot3D

Dr. Monica VanDieren from Robert Morris will present.

Abstract: CalcPlot3D is a free, online applet which provides students opportunities to dynamically visualize and experiment with 3D transformations, rotations, and computations of multivariable calculus concepts. VanDieren is PI on a collaborative NSF Grant No. 1523786 which aims to (1) develop and test a series of new visual concept explorations and applications in CalcPlot3D; (2) expand the features of CalcPlot3D to accommodate the new concept explorations and address applications in differential equations, linear algebra, physics, and engineering; and (3) develop and test an assessment tool to measure student understanding of multivariable calculus concepts. In this presentation, she will cover some of the features of CalcPlot3D and report on preliminary research on student understanding of the cross product.

Date: 3/28/2017

Time: 11:30AM-12:30PM

Place: 315 Armstrong Hall

All are welcome.

## Ananthnarayan Hariharan

Idealizations and Connected sums

Abstract: We will begin with an introduction to Gorenstein rings using partial derivatives.

Two special constructions are idealizations and connected sums.

The goal of this talk is to understand the connection between them.

This talk will have many illustrative examples, and should be accessible to graduate students.

Date: 3/28/2017

Time: 4:00PM-5:00PM

Place: 315 Armstrong Hall

All are welcome.

## Jerzy Weyman

From quiver representations to cluster algebras

Weyman got his Ph.D. in Mathematics from Brandeis University in 1980. His interests include several branches of algebra: Commutative Algebra, Algebraic Geometry, Representation Theory and Invariant Theory. After working for five years at the Institute of Mathematics of the Polish Academy of Sciences, he joined the faculty of Northeastern University in Boston. Since 2013, he is Joan and Stuart Sydney Professor of Mathematics at the University of Connecticut. Professor Weyman was the recipient of the Kuratowski Prize of the Polish Mathematical Society in 1983. He was awarded the Humboldt Research Prize in 2011. He was the recipient of the 2015 Wacław Sierpiński Medal of the Polish Mathematical Society which is given out annually to recognize Polish mathematicians for their outstanding work and scientific achievements in their fields.

Abstract: Pdf

Date: 3/16/2017

Time: 4:00PM-5:00PM

Place: 315 Armstrong Hall

All are welcome.

## Seyfi Turkelli

Counting Field Extensions with Bounded Discriminant

Abstract:In this talk, I will talk about the problem of counting fields with bounded discriminant. After introducing the problem and surveying the important related results, I will talk about its historical connection with Fermat’s Last Theorem, and its important place in the research in number theory. I will conclude the talk with a recent result and the sketch of its proof.

Date: 3/15/2017

Time: 3:00PM-4:00PM

Place: 313 Armstrong Hall

All are welcome.

## RUME Seminar

Student-centred teaching with the Extreme Apprenticeship method

Drs. Johanna Rämö and Jokke Häsä from the University of Helsinki will present

Abstract: Extreme Apprenticeship is a novel student-centred teaching method for large classes with hundreds of students. Its theoretical background is in situated view on learning and Cognitive Apprenticeship. In XA, students participate in activities that resemble those of professional mathematicians. The key elements are instructional scaffolding and continuous bi-directional feedback. Students are guided in their work by undergraduate/graduate TAs. In our talk, we introduce the XA method, and tell how the professional development of TAs has been organised.

Date: 3/3/2017

Time: 2:30PM-3:30PM

Place: 315 Armstrong Hall

All are welcome.

## Tokuji Araya

Topological approach to modeling spatial cognition

Date: 2/8/2017

Time: 4:00PM-5:00PM

Place: 315 Armstrong Hall

Abstract:The Auslander-Reiten quiver is one of the crucial tools to investigate the category of finitely generated modules over noetherian rings. It is an oriented graph whose vertices are indicated by indecomposable modules, and whose arrows are indicated by irreducible homomorphisms. In this talk, we will recall the notion of Auslander-Reiten quiver and calculate some examples.

All are welcome.

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