Open problems in dynamical systems

Speaker: 

Anton Gorodetski

Institution: 

UC Irvine

Time: 

Tuesday, October 16, 2012 - 2:00pm to 3:00pm

Location: 

RH 440R

We will review the inventory of open problems related to hyperbolic and partially hyperbolic dynamics (including the trace map dynamics), conservative dynamics, complex dynamics, piecewise translations, and convolutions of singular measures that are in a focus of our seminar interests (or are natural candidates for this status). Many of the problems are suitable for beginning graduate students. 
 
 

Modeling Quasicrystals: An application of hyperbolic dynamics

Speaker: 

May Mei

Institution: 

UC Irvine, Math. Department

Time: 

Wednesday, October 10, 2012 - 4:00pm to 5:00pm

Location: 

Rowland Hall 306

Talk Abstract:
The Nobel Prize-winning discovery of quasicrystals has spurred much work in aperiodic sequences and tilings. One such example is the family of one-dimensional discrete Schrödinger operators with potentials given by primitive invertible substitutions on two letters, which are a one-dimensional model of quasicrystals. We prove results about spectral properties of these operators using tools from hyperbolic dynamics.

 

Some results concerning the extended CMV matrix

Speaker: 

Darren Ong

Institution: 

Rice

Time: 

Thursday, January 17, 2013 - 2:00pm to 3:00pm

Host: 

Location: 

RH 306

The CMV matrix is a unitary operator on $\ell^2(\mathbb N)$ that is a central tool in the study of orthogonal polynomials on the unit circle. One may view it as a unitary analogue of the Jacobi matrix. We may extend the CMV matrix to be a unitary operator on $\ell^2(\mathbb Z)$. It is more natural to consider the extended CMV matrix in certain contexts: for example, if we wish to generate CMV matrices dynamically. The extended CMV matrix also plays an important role in the study of quantum random walks.

In this talk, we will discuss a Gordon lemma for the CMV matrix (The Gordon lemma is an important tool in the study of Jacobi matrices, used to rule out the possibility pure point spectrum). We will also discuss some results pertaining to the H\"older-continuity of the spectrum of the extended CMV matrix.

Degenerations of Ricci-flat Calabi-Yau manifolds

Speaker: 

Yuguang Zhang

Institution: 

Capital Normal Univ. Beijing

Time: 

Tuesday, October 16, 2012 - 4:00pm

Location: 

RH 306

In this talk, we study  the Gromov-Hausdorff convergence of  Ricci-flat metrics   under degenerations of Calabi-Yau manifolds. More precisely, for a family of polarized Calabi-Yau manifolds degenerating to a singular Calabi-Yau variety,  we prove that  the Gromov-Hausdorff limit of Ricci-flat kahler metrics on them is unique.

On some inequalities for solutions of Ricci flow

Speaker: 

Bennett Chow

Institution: 

UC San Diego

Time: 

Tuesday, October 23, 2012 - 4:00pm

Location: 

RH 306

In this expository talk, we discuss some inequalities holding
for certain solutions of Ricci flow. Ricci flow is a form of the heat
equation for Riemannian metrics. So techniques from the study of the
heat equation apply. Examples of basic inequalities include the
Li-Yau inequality for positive solutions of the heat equation, which
motivated the Harnack inequalities of Hamilton and Perelman for Ricci
flow. Fundamental inequalities of Perelman are for the entropy and for
the reduced volume. Moreover, there are many other inequalities which
hold for certain classes of solutions, such as those proved by
Hamilton, Perelman, and others.

Stability of solutions of Ricci flow

Speaker: 

Michael Williams

Institution: 

UCLA

Time: 

Tuesday, December 4, 2012 - 4:00pm to 5:00pm

Location: 

RH 306

The Ricci flow is an important tool in geometry, and a main
problem is to understand the stability of fixed points of the flow and the
convergence of solutions to those fixed points. There are many approaches
to this, but one involves maximal regularity theory and a theorem of
Simonett. I will describe this technique and its application to certain
extended Ricci flow systems. These systems arise from manifolds with
extra structure, such as fibration or warped product structures, or Lie
group structures.

Volume of nodal sets of eigenfunctions

Speaker: 

Hamid Hezari

Institution: 

UC Irvine

Time: 

Friday, December 7, 2012 - 4:00pm

Location: 

MSTB 120

Yau's conjecture states that the volume of the nodal set of
Laplace eigenfunctions on a compact Riemannian manifold is comparable to
the square root of the corresponding eigenvalue. Donnelly and Fefferrman
proved Yau's conjecture for real analytic metrics but the conjecture stays
widely open for smooth metrics specially in dimensions n>2. Recently
Sogge-Zelditch and Colding-Minicozzi have established new lower bounds for
the volume of the nodal sets. In this talk we give a new proof of
Colding-Minicozzi's result using a different method. This is a joint work
with Christopher Sogge and Zuoqin Wang.

Pages

Subscribe to UCI Mathematics RSS