NTSGrad Fall 2024/Abstracts

This page contains the titles and abstracts for talks scheduled in the Fall 2024 semester. To go back to the main GNTS page for the semester, click here.

9/10

Ivan Aidun

Rational Points on Curves, an Introduction to Arithmetic Geometry

Arithmetic geometry is an area of number theory that uses geometry to answer questions about when multivariable polynomials have integer or rational solutions. Already, even the simplest case, finding rational points on curves, offers many interesting facets worth exploring. In this talk I'll introduce several facets of the world of finding points on curves. Although I won't be able to discuss any topic in great depth, I hope to say at least a little bit about: finding points everywhere locally, why are elliptic curves groups, and why does the genus of a curve affect the rational points.

9/17

Amin Idelhaj

Random Walk on Groups

I'll give a random walk through some topics surrounding random walk on finite groups: Fourier analysis, spectral gaps, isoperimetric inequalities, and expander graphs.

9/24

Chenghuang Chen

Exponential Sums in Analytic Number Theory

I will mainly focus on van der Corput's B process for exponential sums in order to fit Thursday's NTS talk. If I have enough time, I will also talk about some related concepts in Montgomery's book "Ten Lectures on the Interface of Analytic Number Theory and Harmonic Analysis".

10/1

Eiki Norizuki

Hodge Numbers of Birational Calabi-Yau Manifolds

This is a prep talk for Thursday's NTS talk. In 1995, Kontsevich introduced motivic integration to prove that Hodge numbers of Birational Calabi-Yau Manifolds are equal. There is an alternative proof using other tools and I will try to outline some of the ingredients of this approach. I may talk about classical Hodge theory, Weil conjectures, p-adic integrations and p-adic Hodge theory.

10/8

Yihan Gu

Surjectivity of l-adic Galois representations

Consider a non-CM elliptic curve over the rationals. Let l be a prime number, we have a Galois group acting on the l-torsion group, which gives us a Galois representation. According to Serre, this representation is surjective for sufficiently large l. On Tuesday, I will introduce an algorithm given by David Zywina which tells us how to find the finite set of primes such that the representation is not surjective for every prime in the set. I will also talk about improved upper bounds of the Serre's result. If we have time, I will briefly introduce another algorithm on Abelian surfaces by Luis V. Dieulefait.

10/15

Jiaqi Hou

Residue symbols and Gauss sums

In this talk, I will introduce the definitions and basic properties of residue symbols and Gauss sums. I will first talk about the evaluations of quadratic Gauss sums and the proof based on the Poisson summation formula used by Dirichlet. I will also discuss cubic residue symbols and cubic Gauss sums, and quartic or n-th power residue symbols if time permits.

10/22

Caroline Nunn

Why is j((1+√-163)/2) a rational number?

The j-invariant is an important invariant of elliptic curves. For an elliptic curve defined over the complex numbers, the j invariant can be calculated using a holomorphic function (in fact, a modular function) called Klein's j function. We will look at the rationality (and more generally the algebraicity) of certain values of the j function and see that this question is closely related to the theory of complex multiplication, that is, the theory of elliptic curves whose endomorphism ring is larger than expected.