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.

Mathematical quasicrystals and their spectral properties

Speaker: 

Anton Gorodetski

Institution: 

UC Irvine

Time: 

Friday, November 30, 2012 - 4:00pm

Location: 

MSTB 120

Penrose tilings and substitution sequences, spectral properties of operators in Hilbert space and dynamical systems, fractals and convolutions of singular measures - we will see how all these topics meet in the study of mathematical quasicrystals. 

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