# School of Mathematics

## The (Unreasonable) Effectiveness of (Hyperbolic) Geometry

## Periods Over Spherical Subgroups: An Extension of Some of the Langlands Conjectures

Periods of automorphic forms over spherical subgroups tend to: (1) distinguish images of functorial lifts and (2) give information about L-functions.

This raises the following questions, given a spherical variety X=H\G: Locally, which irreducible representations admit a non-zero H-invariant functional or, equivalently, appear in the space of functions on X? Globally, can the period over H of an automorphic form on G be related to some L-value?

## QUESTION SESSION ON GRASSMANNIANS, POLYTOPES AND QUANTUM FIELD THEORY

## A PRG for Gaussian Polynomial Threshold Functions

We define a polynomial threshold function to be a function of the form f(x) = sgn(p(x)) for p a polynomial. We discuss some recent techniques for dealing with polynomial threshold functions, particular when evaluated on random Gaussians. We show how to use these ideas to produce a pseudo random generator for degree-d polynomial threshold functions of Gaussians with seed length poly(2^d,log(n),epsilon^{-1}) .

## On Functoriality; on the Correspondence; and on Their Relation, Part 1

## On the Fourier Spectrum of Symmetric Boolean Functions

It is well-known that any Boolean function f:{-1,+1}^n \to {-1,+1} can be written uniquely as a polynomial f(x) = \sum_{S subset [n]} f_s \prod_{i in S} x_i. The collection of coefficients (f_S's) this expression are referred to (with good reason) as the Fourier spectrum of f. The Fourier spectrum has played a central role in modern computer science by converting combinatorial and algorithmic questions about f into algebraic or analytic questions about the spectrum.

## Analytic Geometry Over F_1

I'll talk on work in progress on algebraic and analytic geometry over the field of one element F_1. This work originates in non-Archimedean analytic geometry as a result of a search for appropriate framework for so called skeletons of analytic spaces and formal schemes, and is related to logarithmic and tropical geometry. I'll explain what analytic spaces over F_1 are, and will describe non-Archimedean and complex analytic spaces which are obtained from them.