CRYPTOGRAPHY DAY

Institution: 

UCI

Time: 

Tuesday, April 19, 2016 - 9:30am to 5:30pm

Host: 

Location: 

Calit2, Room 3008

9:30-10     Welcome and refreshments
10-10:45    Hovav Shacham (UCSD) will speak on 
                 "Elliptic curves in kleptography: 
                  The case of the Dual EC random number generator"
10:45-11    Refreshments
11-12         GENERAL AUDIENCE TALK: Hovav Shacham (UCSD) will speak on 
                  "Why making elections trustworthy is a computer science problem"
2-2:45        Hovav Shacham (UCSD) will speak on 
                  "Subnormal floating point and abnormal timing"
2:45-3        Refreshments
3-4             Rafail Ostrovsky (UCLA) will speak on 
                  "Delegation of computation into the cloud" Part 1
4-4:30        Refreshments
4:30-5:30   Rafail Ostrovsky (UCLA) will speak on 
                  "Delegation of computation into the cloud" Part 2

Website: http://www.math.uci.edu/~asilverb/CryptoDayApril2016.html

Riemannian manifolds with positive Yamabe invariant and Paneitz operator

Speaker: 

Yueh-Ju Lin

Institution: 

University of Michigan

Time: 

Tuesday, April 26, 2016 - 4:00pm

Location: 

RH 306

For a compact Riemannian manifold of dimension at least three, we know that positive Yamabe invariant implies the existence of a conformal metric with positive scalar curvature. As a higher order analogue, we seek for similar characterizations for the Paneitz operator and Q-curvature in higher dimensions. For a smooth compact Riemannian manifold of dimension at least six, we prove that the existence of a conformal metric with positive scalar and Q-curvature is equivalent to the positivity of both the Yamabe invariant and the Paneitz operator. In addition, we also study the relationship between different conformal invariants associated to the Q-curvature. This is joint work with Matt Gursky and Fengbo Hang.

 

Two numerical aspects of the Toda lattice

Speaker: 

Tom Trogdon

Institution: 

UC Irvine

Time: 

Friday, April 29, 2016 - 11:00am to 12:00pm

Host: 

Location: 

RH306

The Toda lattice is the prototypical discrete-space, continuous-time completely integrable Hamiltonian system.  It was introduced by Morikazu Toda in 1967 and analyzed in detail by Flaschka in 1974.  The bi-infinite Toda lattice can be solved with its associated inverse scattering transform (IST).  The IST is closely tied to the interpretation of the flow as an isospectral deformation of a bi-infinite tridiagonal matrix.  The Toda lattice has a completely integrable counterpart for finite symmetric and Hermitian (dense) matrices.  And due the the isospectral nature of the flow, it can be used as an eigenvalue algorithm. This talk has two parts. First, I will discuss the numerical computation of the IST for the Toda lattice by solving Riemann--Hilbert problems numerically.  Second, I will show that the time, called the halting time, it takes for the Toda lattice to compute the largest eigenvalue of a random matrix is universal --- the rescaled halting time converges to a universal distribution.

The random interchange process on the hypercube

Speaker: 

Roman Kotecky

Institution: 

University of Warwick

Time: 

Tuesday, March 8, 2016 - 3:00pm to 4:00pm

Host: 

Location: 

RH 340P

We study random permutations of the vertices of a hypercube  given by products of (uniform, independent) random transpositions on edges.  We establish the existence of a phase transition accompanied by emergence of cycles of diverging lengths. The problem is motivated by phase transitions in quantum spin models. (Joint work with Piotr Miłoś and Daniel Ueltschi.)

singular continuous spectrum for singular potentials

Speaker: 

Fan Yang

Institution: 

Ocean Univeristy, visiting UCI

Time: 

Thursday, February 4, 2016 - 2:00pm

Location: 

RH 340P

For singular operators of the form (H_{\alpha,\theta}u)_n=u_{n+1}+u_{n-1}+ \frac{g(\theta+n\alpha)}{f(\theta+n\alpha)} u_n, we prove such operators have purely singular spectrum on the set {E: \delta{(\alpha,\theta)}>L(E)\}, where f and g are both analytic functions.

Compressed Modes for Differential Equations and Physics

Speaker: 

Russel Caflisch

Institution: 

UCLA

Time: 

Thursday, April 21, 2016 - 2:00pm to 3:00pm

Host: 

Location: 

NS2 1201

Much recent progress in data science (e.g., compressed sensing and matrix completion) has come from the use of sparsity and variational principles. This talk is on transfer of these ideas from information science to differential equations and physics. The focus is on variational principles and differential equations whose solutions are spatially sparse; i.e. they have compact support. Analytic results will be presented on the existence of sparse solutions, the size of their support and the completeness of the resulting “compressed modes”. Applications of compressed modes as Wannier modes in density functional theory and for signal fragmentation in radio transmission will be described.

Singular continuous spectrum

Speaker: 

Fan Yang

Institution: 

Ocean University, visiting UCI

Time: 

Thursday, January 14, 2016 - 2:00pm

Location: 

rh 340p

For singular operators of the form (H_{\alpha,\theta}u)_n=u_{n+1}+u_{n-1}+
\frac{g(\theta+n\alpha)}{f(\theta+n\alpha)} u_n, we prove such operators
have purely singular continuous spectrum on the set
{E: \delta{(\alpha,\theta)}>L(E)\}, where f and g are both analytic functions
on T.

 

 

 

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