Dr. Jim Carlson, president of the Clay Mathematics Institute in Cambridge, Mass., will present at BYU’s Math Department Colloquium Tuesday, October 26.

# Author: Staff

## Colloquium: Dr. Jim Carlson

## FOCUS on Math: Dr. Michael Dorff

Dr. Michael Dorff of BYU’s Department of Mathematics is the recipient of this year’s Kenneth C. Savage Distinguished Teaching Award and will present a lecture on Thursday, October 21 at 4:00 in 3108 JKB.

**Title: **Soap bubbles, multiple dimensions and how math can get you a great job.

## FOCUS on Math: Dr. John Friedlander

Dr. John Friedlander, University of Toronto

"A Brief History of Primes"

Problems about prime numbers have long fascinated mathematicians, both professional and amateur. We will discuss some of the problems, old and new, that have been posed about these numbers, some of the methods that have been used to attack them, and some of the successes and failures along the way. We also touch on primality and the factorization of integers and their use in internet and banking security. The lecture is intended to be accessible to all students taking some undergraduate mathematics.

## Colloquium: Dr. Vianey Villamizar

**Date:** Tuesday, October 5.

**Title: **Multiple Acoustic Scattering from Complexly Shaped Objects

**Abstract:** The classical exterior boundary value problem (BVP) for multiple acoustic scattering is reformulated as an equivalent interface problem. The interface *B* of the new problem is formed by separate artificial boundaries *B ^{m}* enclosing the different obstacles. A rigorous proof of the equivalence between these two problems is given for smooth interfaces

*B*of arbitrary shape. This equivalent BVP is numerically solved by coupling a Dirichlet-to-Neumann boundary condition on the interface

^{m}*B*with a second order finite difference technique, which is supported by novel elliptic grids. This leads to a drastic reduction of storage and computational cost and greatly simplifies the grid generation process.

As a validation of the technique, a second order convergence of the approximate far-field pattern to the exact one for two circular cylindrical obstacles is easily obtained. Since inverse scattering problems are typically solved using iterative methods that require solution of direct problems, our results may have an impact on current techniques employed in identification of medical conditions in the human brain, in the detection of cancerous cells, and in radar imaging among many others.

## Number Theory Seminar

We consider a variant of the Bombieri-Vinogradov theorem. Rather than average over all moduli q in an interval, we average over q = f(k), where f is a polynomial with integer coefficients.

## Colloquium: Dr. Shaun Fallat

Dr. Shaun Fallat of the University of Regina will be the speaker at this fall’s second colloquium September 21.

A matrix is called totally positive (resp. totally nonnegative) if all of its minors are positive (resp. nonnegative). This important class of matrices grew out of three separate applications: Vibrating systems, interpolation and statistics.

## Colloquium: Dr. Vadim Kaloshin

Dr. Vadim Kaloshin of the University of Maryland and Penn State University will present the first colloquium of the Fall Semester.

The number of central configurations of the five-body problem is finite positive, except perhaps if masses satisfy certain algebraic relationships.

## To Be or Not To Be a Math Major/Minor?

Join the Math Department for a pizza social September 16th to learn about opportunities awaiting you when you major or minor in math!