Professor Dan Cranston 1/31/2013

Coloring claw-free graphs with
Delta(G) - 1 colors

Date: 1/31/2013
Time: 3:45-4:45 PM
Place: 315 Armstrong Hall

Abstract: Borodin and Kostochka conjectured that every graph with
maximum degree Delta at least 9, and with no clique on Delta vertices has
chromatic number at most Delta - 1. We prove this conjecture for
claw-free graphs, i.e., those with no induced K_{1,3}. This is joint
work with Landon Rabern, of Arizona State University.

Date, Location: 

Professor Zhengchang Su 11/14/2012

Large scale annotation of cis-regulatory sequences in prokaryotic

Date: 11/14/2012
Time: 2:30-3:30 PM
Place: 315 Armstrong Hall

Abstract: Although we now can gain a fairly good understanding of coding
sequences or genes in any newly sequenced prokaryotic genomes thanks to
the development of accurate and efficient gene-finding tools, we know very
little about cis-regulatory sequences or transcription factor binding
sites in the vast majority of sequenced genomes owing to the lack of an
accurate and efficient computational method for their predictions. To
achieve the goal of computational annotation of cis-regulatory binding
sites in all sequenced prokaryotic genomes, we are developing algorithms
and tools for genome-wide de novo prediction of cis-regulatory binding
sites in a large scale through comparative genomics analysis. In my talk,
I will introduce our recent development of computational algorithms and
tools for the simultaneous prediction of cis-regulatory binding sites in a
group of prokaryotic genomes.

Date, Location: 

Professor Anthony Hilton 11/9/2012

Bounds on the simple graph and multigraph (r,s,a,t)-threshold numbers

Date: 11/9/2012
Time: 3:30-4:30 PM
Place: 315 Armstrong Hall

Abstract can be downloaded as a PDF

Date, Location: 

Professor Bolian Liu 11/8/2012

The sum of Laplacian

Date: 11/8/2012
Time: 3:30-4:30 PM
Place: 315 Armstrong Hall

Let $G$ be a simple graph with $n$ vertices and $e(G)$ edges. A.E.
Brouwer et al. conjectured that the sum of the $k$ largest Laplacian
eigenvalues of $G$ is at most $e(G)+{k+1 \choose 2}$, where $1\leq
k\leq n$. In this talk , we survey the works for the proof of the conjecture.

Date, Location: 

Professor Marcus Wunsch 10/31/2012

The Hunter-Saxton system and
the geodesics on (pseudo-)spheres

Date: 10/31/2012
Time: 3:30-4:30 PM
Place: 315 Armstrong Hall

Abstract can be downloaded as a PDF

Date, Location: 

Professor Stacey Levine 10/24/2012

Image Fusion using
Gaussian Mixture Models

Date: 10/24/2012
Time: 3:30-4:30 PM
Place: 315 Armstrong Hall

A number of recent works have demonstrated that using
patches, in lieu of pixels, as image features can more effectively
perform various techniques such as denoising, deblurring, inpainting
and super-resolution. This if often carried out by sparsely
representing the images patches in appropriately defined, possibly
redundant, dictionaries. Yu, Sapiro, and Mallat showed that a related
but more stable solution can be found by estimating the patches using
Gaussian Mixture Models (GMMs), particularly when solving ill-posed
inverse problems such as deblurring and super-resolution. In this talk
we discuss how this GMM approach can be can be used for fusing images
of the same field of view, suffering from any or all of the
above-mentioned degradations. The fusion model retains many of the
nice properties of the single image GMM model such as its equivalence
to finding an optimal sparse representation in a PCA dictionary, and
can be simply modified to handle spatially varying features, including
geometric features (e.g. edges, smooth regions, and textures) as well
as spatially varying noise levels. We will also discuss how some of
these results fair with respect to comparable variational approaches.

Date, Location: 

Professor Keith Weber 10/04/2012

Reading and comprehending
mathematical proofs

Date: 10/04/2012
Time: 4:00-5:00 PM
Place: 315 Armstrong Hall

In advanced undergraduate mathematics classes, students spend a
substantial amount of time studying mathematical proofs. Yet it is generally
accepted that most students have difficulty understanding the proofs that
they read. In this talk, I will discuss (a) what it means for a student to
understand a mathematical proof and how this understanding can be assessed,
(b) unproductive beliefs about proof held by students that inhibit
understanding, (c) strategies that students can use when reading a proof
that will increase understanding, and (d) lessons learned from experiments
in which we attempted to teach students to use these strategies.

Date, Location: 

Professor Charis Tsikkou 9/24/2012

Conservation Laws with no Classical Riemann Solutions: Existence of
Dafermos profiles for singular shocks.

Date: 9/24/2012
Time: 3:30 PM
Place: 315 Armstrong Hall

The basic tool in the construction of solutions to the Cauchy
problem for conservation laws with smooth initial data is the Riemann
problem. In this talk I will review the results obtained for the solutions to the
Riemann problem and present a system of two equations derived from
isentropic gas dynamics with no classical solution. I will then use the
blowing-up approach to geometric singular perturbation problems to show
that the system exhibits unbounded solutions (singular shocks) with
Dafermos profiles.

Date, Location: 

Professor Richard Price 9/20/2012

Binary Black Hole Inspiral: Legends
of the Fall

Date: 9/20/2012
Time: 3:30 PM
Place: G09 White Hall

*Refreshments will be served at 3PM.
This is a talk cosponsored by the Department of Mathematics and the Department of Physics. Any faculty or students interested in meeting with Dr. Price should contact me ( or Joann ( to reserve some time on Friday, 9/21. We will have a lunch with him at 12PM Friday (please join us) and there will be time for meetings after that (roughly 1-4p) to meet individually. If you have some interest in this area I encourage you to schedule a time.

Professor Price's flyer for the colloquium is here

Date, Location: 

Professor Moseley 9/6/2012

Date: 9/6/2012
Time: 4:30 PM
Place: 315 Armstrong Hall

I will be giving an undergraduate colloquium on Thursday
September 6, 2012 in Armstrong 315 at 4:30 to help everyone to
understand the "Linear Operator Theory" approach to Math 251 and Math
261. See attached. Not all in Math 251 and Math 261 is Linear Theory,
but enough is to make this approach reasonable, especially for the
engineers. About 90-99% of the students in Math 251 and Math 261 are
engineers. They need to know what a Linear System is from a mathematical
perspective. This begins with the definition of a vector space as an
abstract algebraic structure. Students (engineering and others) find
this hard, but math avoidance is not the answer. In my classes I am
trying to keep them from getting stuck in 3 space. (Please help me.
I'm stuck in 3 space and I can't get out.) The sooner they are exposed
to the Euclidean view of mathematics, the better. This does not
necessarily mean a lot of proofs. I do very few proofs. You and all
of your students are invited. I have enough overheads for 2-3 hours. However, I have cut
it down to a 10-20 minute talk plus questions. Hope to see you there.

PDF for colloquium can be downloaded here

Date, Location: 


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