Department of Mathematics,
University of California San Diego

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Analysis Seminar

Peter Hintz
UC Berkeley

Stability of Minkowski space and asymptotics of the metric

Abstract:

I will explain a new proof of the non-linear stability of the Minkowski spacetime as a solution of the Einstein vacuum equation. The proof relies on an iteration scheme at each step of which one solves a linear wave-type equation globally. The analysis takes place on a suitable compactification of $\mathbb{R}^4$ to a manifold with corners whose boundary hypersurfaces correspond to spacelike, null, and timelike infinity; I will describe how the asymptotic behavior of the metric can be deduced from the structure of simple model operators at these boundaries. This talk is based on joint work with Andras Vasy.

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AP&M 7321

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Department of Mathematics,
University of California San Diego

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Math 258 - Differential Geometry

Xin Dong
UCR

Bergman kernel and its boundary asymptotics

Abstract:

We study variations of the Bergman kernel and their asymptotic behaviors at degeneration. For a holomorphic family of hyperelliptic nodal or cuspidal curves and their Jacobians, we announce our results on the Bergman kernel asymptotics near various singularities. For genus-two curves particularly, asymptotic formulas with precise coefficients involving the complex structure information are written down explicitly. Time permitting, we would like to talk about the equality part of the Suita conjecture as an application.

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AP&M 5829

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Department of Mathematics,
University of California San Diego

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Math 278C: Optimization and Data Science Seminar

Todd Kemp
UCSD

Entanglement of Symmetric Tensors

Abstract:

Entanglement is a core concept in quantum mechanics and quantum information theory. Put simply: a tensor is entangled if is not a product state. Measuring precisely how much entanglement a given tensor has is a big question with competing answers in the physics community. One natural measure is the {\bf geometric measure of entanglement}, which is a version of the Hilbert--Schmidt distance of the given tensor from the set of product states. It can also be described as the log of the spectral norm.

In 2009, Gross, Flammia, and Eisert showed that, as the mode of the tensor grows, the geometric measure of entanglement of a random tensor is, with high probability, very close to the theoretical maximum. In this talk, I will describe my joint work with Shmuel Friedland on the analogous situation for symmetric tensors. While symmetric tensors are inherently entangled, it turns out their maximum geometric measure of entanglement is exponentially smaller than for generic tensors. Using tools from representation theory and random matrix theory, we prove that, nevertheless, random symmetric tensors are, with high probability, very close to maximally entangled.

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AP&M 5829

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Department of Mathematics,
University of California San Diego

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MATH 288 - Probability & Statistics

Lucian Beznea
IMAR

Invariant, super and quasi-martingale functions of a Markov process

Abstract:

We identify the linear space spanned by the real-valued excessive functions of a Markov process with the set of those functions which are quasimartingales when we compose them with the process. Applications to semi-Dirichlet forms are given. We provide a unifying result which clarifies the relations between harmonic, co-harmonic, invariant, co-invariant, martingale and co-martingale functions, showing that in the conservative case they are all the same. The talk is based on joint works with Iulian Cimpean (Bucharest) and Michael Roeckner (Bielefeld).

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AP&M 6402

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Department of Mathematics,
University of California San Diego

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Math 209 - Number Theory

Jesse Elliott
CSU Channel Islands

Extensions of the prime number theorem and the Riemann hypothesis

Abstract:

We provide two asymptotic continued fraction expansions of the
prime counting function. We also develop a ``degree'' calculus that
enables us to strengthen the connections between various reformulations
and extensions of the Riemann hypothesis.

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AP&M 7321

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