“Horn Inequalities: Old and New”, by Professor Dan Timotin; 4/26 at 4:00pm

The Mathematics Department’s Distinguished Visiting Professor

Dan Timotin, Institute of Mathematics of the Romanian Academy

Tuesday, April 26th 4:00 P.M.
ROOM 372 in the Olin Science Building

Abstract: If A and B are self-adjoint matrices, what is the relation between the eigenvalues of A, those of B, and those of A+B? The talk will describe the unexpected ramifications in various areas of mathematics of this old problem. Some recent developments, mostly pertaining to operator theory, will also be presented.

Contraction-Based Approach to Tensor Isomorphism, an Honors Thesis Defense by Anh Kieu ’22 Wednesday 4/20 at 4:00pm


Contraction-based approach to tensor isomorphism

Presented by:

Anh Kieu ‘22

Thesis Advisor: Pete Brooksbank

2nd Reader: Ben Vollmayr-Lee
Wednesday, April 20, at 4:00 PM
OLIN 372

Everyone is welcome to attend.

Abstract: Tensors are natural generalizations of linear transformations to arbitrary “frames” of vector spaces. Just as how a linear transformation can be represented by a matrix, choosing a reference frame allows a tensor to be represented by a multiway array. A fundamental question is to decide when two multiway arrays represent the same tensor relative to different reference frames. This question is commonly known as the tensor isomorphism problem. In this Honors Thesis, we developed a new approach to testing (non)-isomorphism of tensors that uses detailed local information to detect differences in global tensor structure. The method assumes isomorphism invariant “labels” for lower valence tensors can be computed, and then compares two given tensors by computing their so-called “contraction labels.” We implemented this method in a computer algebra system called Magma and applied it to 4-qubit states in QIT as a proof of concept.

“Lies, Damn Lies, and…Olympic Judging Systems”, Colloquium by Professor John Emerson Thursday 4/21 at 12:00pm

Mathematics Department, Student Colloquium Series


PIZZA SERVED from 11:30 -11:55 in front of Hislop Family Auditorium


Lies, Damn Lies, and…Olympic Judging Systems

Presented by

John W. Emerson
Director of Graduate Studies
 Department of Statistics and Data Science – Yale University

Thursday, April 21, 2022

12:00 P.M.        HOLMES HALL – 116 Hislop Family Auditorium

Abstract: This talk considers aspects of Olympic judging systems in two different sports, diving and figure skating.  The former sport can boast of complete transparency, with the identities of the judges tied to scores available to the general public.  The latter sport, in contrast, has struggled to evolve since the judging scandal of the Salt Lake City Olympic Games.

BIO: John W. Emerson is the Director of Graduate Studies in the Department of Statistics and Data Science. His primary interests are in computational statistics and graphics, and his applied work ranges from topics in sports statistics to bioinformatics, environmental statistics, and Big Data challenges. He teaches a range of undergraduate and graduate courses from “Introductory Data Analysis” to “Statistical Case Studies.” He is the author of several R packages including bcp (for Bayesian change point analysis), bigmemory and sister packages (towards a scalable solution for statistical computing with massive data), and gpairs (for generalized pairs plots). He has served in various leadership roles in several sections of the American Statistical Association.  He misses international travel and loves to cook.