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Seminars and Colloquiums
for the week of April 17, 2017


SPEAKER:

Conrad Plaut, UTK, Monday
Jim Coykendall, Clemson, Monday
Cheng Wang, UMass, Dartmouth, Monday
Phil Bowers, Florida University, Wednesday
Cory Hauck, ORNL and UTK, Wednesday
Kevin Sonnanburg, UTK, Thursday
Dr. Hem Raj Joshi, Xavier University, Friday
Haya Kaspi, Technion, Friday


TEA TIME -
3:00 pm – 3:30 pm
Monday, Tuesday, and Wednesday: Ayres 401
Hosted by: Tricia Phillips


Monday, April 17th

TOPOLOGY/GEOMETRY SEMINAR

Title: Discrete Homotopy Theory
Speaker: Conrad Plaut, UTK
Time: 2:30p - 3:20p
Room: Ayres 113
Discrete homotopy theory replaces continuous paths and homotopies with discrete versions, allowing one to understand the fundamental group at a given scale in a metric space. I’ll give the basic definitions and constructions, then state "curvature-free" generalizations of some well-known finiteness theorems for Riemannian manifolds. If I have time I’ll discuss some preliminary results concerning extending these ideas to be dependent only on the topology of the underlying space rather than the metric. This leads to some new topological invariants that are closely connected to the geometric complexity of geodesic metrics that a compact space may have. This work lies at the beautiful interface between geometry and topology, when constraints on one can lead to constraints on the other. The talk will mainly be about fundamentals and ideas, with few technical details.


ALGEBRA SEMINAR

Title: Ideals and Graphs
Speaker: Jim Coykendall, Clemson
Time: 3:35p - 4:25p
Room: Ayres 113
We define the zero-divisor graph of a commutative ring, R, to have its vertex set be the set of nonzero zero divisors of R and we declare that there is an edge between x and y in R if and only if xy=0. D. F. Anderson and P. S. Livingston wrote a (perhaps the) seminal paper on the subject in 1999 and proved (among other things) that the zero divisor graph of R is always connected and has diameter no more than 3. In this talk, we will discuss a related concept where the vertices are taken as ideals in a commutative ring and edges are defined in various ways in an attempt to "pictorially" understand some of the ideal theoretic properties of R. We will discuss different types of edge definitions and some of the graph-theoretic properties that result. We will also glean some information on the ideal structure of R via these graphs.


COMPUTATIONAL and APPLIED MATHEMATICS (CAM) SEMINAR

Title: Preconditioned Steepest Descent (PSD) solver for the Cahn-Hilliard equation coupled with fluid flow
Speaker: Cheng Wang, UMass, Dartmouth
Time: 3:35p - 4:35p
Room: Ayres 405
The preconditioned steepest descent (PSD) solvers are applied to Cahn-Hilliard equation, coupled with certain fluid flow, such as the Hele-Shaw or Stokes equation. With a careful temporal discretization, the numerical scheme corresponds to a generalized gradient flow, and the numerical solution is equivalent to a minimization of a purely convex energy. In particular, due to the semi-implicit treatment of the nonlinear convention term, a linear energy functional is involved associated with the convection part, and this subtle fact greatly simplifies the numerical effort. By using the energy dissipation property, we derive a discrete bound for the solution, as well as an upper-bound for the second derivative of the energy. Furthermore, a geometric convergence rate is shown for the nonlinear PSD iteration applied to the Cahn-Hillird-Flow models, which turns out to be e very sharp theoretical result. Some numerical results are also presented in the talk.


Wednesday, April 19th

ANALYSIS SEMINAR

Title: Cauchy rigidity of circle polyhedra (told in two stories and one question).
Speaker: Phil Bowers, Florida University
Time: 2:30p – 3:20p
Room: 112 Ayres


COMPUTATIONAL and APPLIED MATHEMATICS (CAM) SEMINAR

Title: TBA
Speaker: Cory Hauck, ORNL and UTK
Time: 3:35p - 4:35p
Room: Ayres 113


Thursday, April 20th

DIFFERENTIAL EQUATIONS SEMINARS

Title: TBA
Speaker: Kevin Sonnanburg, UTK
Time: 2:00p – 3:00p
Room: Ayres 113


Friday, April 21st

SIAM Student Chapter Meeting and Short Talk

Title: Research and Teaching at a small university
Speaker: Dr. Hem Raj Joshi, Xavier University
Time: 11:15a - 12:00p
Room: A114
PIZZA will be served!


COLLOQUIUM

Title: Local Times of Markov Processes and Permanental Processes
Speaker: Haya Kaspi, Technion
Time: 3:30pm – 4:30pm
Room: 405 Ayres
Permanental Processes are a certain class of Gamma processes that generalize squared Gaussian processes. One class of Permanentals is connected with Markov processes, their defining parameters are the potential densities of a corresponding Markov process. Permanental processes thus associated with Markov processes are infinitely divisible. We analize the connections of those Permanentals with the local time process, indexed by the states, of the associated Markov process. We deduce sample path properties of one process from the other, using their infinite divisibility and a formula known as the Isomorphism Theorem. Joint work with Nathalie Eisenbaum from CNRS Paris VI


If you are interested in giving or arranging a talk for one of our seminars or colloquiums, please review our calendar.

If you have questions, or a date you would like to confirm, please contact colloquium AT math DOT utk DOT edu


Past notices:

4_10_17.html

4_3_17.html

3_27_17.html

3_20_17.html

3/13/17 - Spring Break

3_6_17.html

2_27_17.html

2_20_17.html

2_13_17.html

2_6_17.html

1_30_17.html

1_23_17.html

1_16_17.html

Winter Break

11_28_16.html

11_21_16.html

11_14_16.html

11_7_16.html

10_31_16.html

10_24_16.html

10_17_16.html

10_10_16.html

10_3_16.html

9_26_16.html

9_19_16.html

9_12_15.html

spring_16.html

fall_15.html

 

last updated: April 2017

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