Separation of roots of random polynomials
Part of the Oxford Discrete Maths and Probability Seminar, held via Zoom. Please see the seminar website for details.
Abstract
What do the roots of random polynomials look like? Classical works of Erdős-Turán and others show that most roots are near the unit circle and they are approximately rotationally equidistributed. We will begin with an understanding of why this happens and see how ideas from extremal combinatorics can mix with analytic and probabilistic arguments to show this. Another main feature of random polynomials is that their roots tend to "repel" each other. We will see various quantitative statements that make this rigorous. In particular, we will study the smallest separation $m_n$ between pairs of roots and show that typically $m_n$ is on the order of $n^{-5/4}$. We will see why this reflects repulsion between roots and discuss where this repulsion comes from. This is based on joint work with Oren Yakir.
An exponential upper bound on induced Ramsey numbers
Abstract
Markov α-potential games
Abstract
We propose a new framework of Markov α-potential games to study Markov games.
We show that any Markov game with finite-state and finite-action is a Markov α-potential game, and establish the existence of an associated α-potential function. Any optimizer of an α-potential function is shown to be an α-stationary Nash equilibrium. We study two important classes of practically significant Markov games, Markov congestion games and the perturbed Markov team games, via the framework of Markov α-potential games, with explicit characterization of an upper bound for αand its relation to game parameters.
Additionally, we provide a semi-infinite linear programming based formulation to obtain an upper bound for α for any Markov game.
Furthermore, we study two equilibrium approximation algorithms, namely the projected gradient- ascent algorithm and the sequential maximum improvement algorithm, along with their Nash regret analysis.
This talk is part of the Erlangen AI Hub.
Will mechanisation change research mathematics?
Abstract
A 2024 collection of articles in the Bulletin of the AMS asked "Will machines change mathematics?", suggesting that "Pure mathematicians are used to enjoying a great degree of research autonomy and intellectual freedom, a fragile and precious heritage that might be swept aside by a mindless use of machines." and challenging readers to "decide upon our subject’s future direction.”
This was a response to growing awareness of the mathematical capabilities of emerging technologies, alone or in combination. These techniques include software such as LEAN for providing formal proofs; use of LLMs to produce credible, if derivative, research papers with expert human guidance; specialist algorithms such as AlphaGeometry; and sophisticated use of machine learning to search for examples. Their development (at huge cost in compute power and energy) has been accompanied by an unfamiliar and exuberant level of hype from well-funded start-ups claiming to “solve mathematics” and the like.
To try and understand what’s going on we look at the factors, whether technical, social or economic, leading to the ongoing adoption and impact, or otherwise, of previous computational interventions in mathematical practice. As an example we consider key decisions made in the early days of computational group theory.