Seminars Sorted by Series

Computer Science/Discrete Mathematics Seminar I

Oct
27
2025

Computer Science/Discrete Mathematics Seminar I

Explicit Lossless Vertex Expanders
Rachel Zhang
11:00am|Simonyi Hall 101 and Remote Access

In this talk, I will describe our construction of the first explicit lossless vertex expanders. These are graphs where every small subset of vertices has about as many neighbors as their sparsity allows. Previously, the strongest known explicit...

Nov
03
2025

Computer Science/Discrete Mathematics Seminar I

New Approach to Matrix Perturbation: Beyond the Worst-Case Analysis
Van H. Vu
11:00am|Simonyi Hall 101 and Remote Access

Matrix-perturbation bounds quantify how the spectral characteristics of a baseline matrix A change under additive noise E. Classical results, including Weyl’s inequality for eigenvalues and the Davis–Kahan theorem for eigenvectors and eigenspaces...

Nov
10
2025

Computer Science/Discrete Mathematics Seminar I

On Beck-Fiala and Komlós Conjectures
Nikhil Bansal
11:00am|Simonyi Hall 101 and Remote Access

A conjecture of Komlós states that the discrepancy of any collection of unit vectors is $O(1)$, i.e., for any matrix A with unit columns, there is a vector x with -1,1 entries such that $|Ax|_\infty = O(1)$. The related Beck-Fiala conjecture states...

Nov
17
2025

Computer Science/Discrete Mathematics Seminar I

Breaking the $\sqrt{n}$ Barrier: New Parallel Algorithms for Finding a Matroid Basis
Aaron (Louie) Putterman
11:00am|Simonyi Hall 101 and Remote Access

Over 40 years ago, Karp, Upfal, and Wigderson posed a central open question in parallel computation: how many adaptive rounds are needed to find a basis of a matroid using only independence queries? Their pioneering work gave an upper bound of $O(...

Nov
24
2025

Computer Science/Discrete Mathematics Seminar I

Why Language Models Hallucinate
Adam Kalai
11:00am|Simonyi Hall 101 and Remote Access

Large language models (LLMs) sometimes generate statements that are plausible but factually incorrect—a phenomenon commonly called "hallucination." We argue that these errors are not mysterious failures of architecture or reasoning, but rather...

Dec
01
2025

Computer Science/Discrete Mathematics Seminar I

How Low Can We Go? Exploring Minimal Assumptions in Quantum Cryptography
Dakshita Khurana
11:00am|Simonyi Hall 101 and Remote Access

In this talk, I will explore the fascinating landscape of assumptions in quantum cryptography—especially, how little we need to assume to build secure quantum protocols. We will cover key cryptographic primitives including quantum encryption...

Dec
08
2025

Computer Science/Discrete Mathematics Seminar I

Trickle-down Theorems for High-dimensional Expanders via Lorentzian Polynomials
Jonathan Leake
11:00am|Simonyi Hall 101 and Remote Access

High-dimensional expanders (HDX) are a generalization of expander graphs which have seen various applications in coding theory, PCPs, pseudorandomness, derandomization, approximate sampling, and beyond. One technique for proving a complex is an HDX...

Jan
29
2026

Computer Science/Discrete Mathematics Seminar I

Direct Product Testers and PCPs from Coset Complexes
Noah Singer
11:00am|Simonyi Hall 101 and Remote Access

Direct-product testers” are used in the design of (some) probabilistically checkable proofs (PCPs), which, in turn, play a fundamental role in modern complexity theory and cryptography. We investigate the direct-product testability of certain...

Feb
02
2026

Computer Science/Discrete Mathematics Seminar I

Disjoint Pairs in Set Systems and the Combinatorics of Low-Rank Matrices
Benjamin Sudakov
11:00am|Simonyi Hall 101 and Remote Access

In this talk, I will discuss the solution to several problems in two closely related settings: set families in 2^[n] with many disjoint pairs, and low-rank matrices with many zero entries.

Highlights include a resolution of an old question of Daykin...

Feb
09
2026

Computer Science/Discrete Mathematics Seminar I

Upper and Lower Bounds for the Linear Ordering Principle
Ilya Volkovich
11:00am|Simonyi Hall 101 and Remote Access

The Linear Ordering Principle (LOP) is a total search problem that generalizes the task of finding the minimum element of a given order to settings in which the order need not be total. Building on this, Korten and Pitassi (FOCS 2024) introduced the...

Mar
02
2026

Computer Science/Discrete Mathematics Seminar I

Color-avoiding Paths
Yuval Wigderson
11:00am|Simonyi Hall 101 and Remote Access

The very first result ever proved about tournaments is due to Rédei, who nearly 100 years ago proved that every tournament contains a Hamiltonian directed path. Since then, questions and results about directed paths in tournaments have become a...

Mar
09
2026

Computer Science/Discrete Mathematics Seminar I

On SNARGs for NP and Nullstellensatz Proofs
Alex Lombardi
11:00am|West Lecture Hall and Remote Access

We revisit the question of whether it is possible to build succinct non-interactive arguments (SNARGs) for all of NP under standard cryptographic assumptions. In particular, we give a candidate non-adaptive SNARG for NP and prove its soundness under...

Mar
16
2026

Computer Science/Discrete Mathematics Seminar I

Probabilistic Guarantees to Explicit Constructions: Local Properties of Linear Codes
Nikhil Shagrithaya
11:00am|Simonyi Hall 101 and Remote Access

We present a general framework for derandomizing random linear codes with respect to a broad class of properties, known as local properties, which encompass several standard notions such as minimum distance, list-decoding, list-recovery, and perfect...

Mar
23
2026

Computer Science/Discrete Mathematics Seminar I

Extended VC-dimension and Radon Type Theorems for Unions of Convex Sets
Noga Alon
11:00am|Simonyi Hall 101 and Remote Access

We define and study an extension of the notion of the VC-dimension of a hypergraph and apply it to establish a Tverberg type theorem for unions of convex sets. We also prove a new Radon type theorem for unions of convex sets, settling an open...

Mar
30
2026

Computer Science/Discrete Mathematics Seminar I

A General Quantum Duality for Representations of Groups with Applications to Quantum Money, Lightning, and Fire
Barak Nehoran
11:00am|Simonyi Hall 101 and Remote Access

Note: This talk will involve quantum computing, cryptography, and representation theory, but no background in any of these will be necessary to understand it. I'll introduce everything from the basics.

Aaronson, Atia, and Susskind (2020) established...