Department of Mathematics
Mathematics Colloquium
Organizer Mailing list: https://groups.google.com/forum/#!forum/ccnymathcolloquium/joinThe Mathematics Department Colloquium typically meets on Thursdays from 12:30 pm to 1:20 pm in NAC 6/113. This will typically be preceded by tea and coffee at noon in the math lounge, and will be followed by lunch. To receive announcements via email, please join our google group
Most recent talks

Thursday, May 03, 2018, 12:30PM, NAC 6/113
Angela Hicks (Lehigh University), Applying Representation Theory to Random WalksWe'll talk about how representation theory can be used to formulaically determine fundamental questions about the rate of convergence of random walks on groups. We'll also discuss some of the difficulties in this approach, here focusing on joint work with Daniel Bump, Persi Diaconis, Laurent Miclo, and Harold Widom studying a simple random walk on the the Heisenberg group mod p (a particularly simple to describe noncommutative group). Analysis of a random walk on the group dates back to Zach, who was considering the effectiveness of certain random number generators. We'll assume a bit of basic group theory and probability, but otherwise aim for an elementary talk.

Thursday, April 19, 2018, 12:30PM, NAC 6/113
Gwen Spencer (Smith College), Influence Maximization in Networks: Spread Models and Optimization MethodsSociologists first introduced the study influence in social networks during the 70's. This inspired mathematicians and computer scientists to propose a number of models about the spread of information and behavior in networks. Given a particular spread process, a natural question is how to choose a small set of individuals who are highlyinfluential (in the sense that their behavior change could cause a large cascade of behavior in the network). This optimization problem has attracted a great deal of theoretical study, but many "scientific facets" of the problem remain open. I'll mention several formal models of spread, mention algorithmic results were they are known, and point out contemporary challenges suggested by human studies in behavioral economics and noisy inputs. Better understanding of this planning problem has the potential to fuel industry efforts in viral marketing, increase the reach of campaigns to promote healthy behaviors, and inform management practices about how to make cooperation more robust.

Thursday, March 29, 2018, 12:30PM, NAC 6/113
Martin Schmoll (Clemson University), Ergodic Eaton Lens configurations in the planeEaton Lenses are flat lenses that are perfect retroreflectors. We study periodic patterns of non overlapping Eaton lenses in the plane. A light ray moving in the plane furnished with a non overlapping pattern of Eaton lenses will keep a particular direction in the complement of the Eaton lenses. In particular for non overlapping lens patterns it makes sense to consider the ergodicity of the set of light rays parallel to a given direction (in the lens complements). We describe several loops in the "space" of non overlapping Eaton lens patterns parameterized by the light direction (in the lens complements), so that, roughly speaking, for almost every point on each loop, i.e. direction, the family of parallel light rays is ergodic. The mathematical framework we employ to study Eaton lens dynamics are halftranslation surfaces. The ergodicity in almost every direction follows from an ergodicity theorem for Z^{d} covers of halftranslation surfaces applied to halftranslation tori.
This is joint work with Krzysztof Fraczek (Torun).