Francesco Fournier-Facio (University of Cambridge)

Are approximate representations close to true representations? This question goes back to back to works of von Neumann, Turing and Ulam, and can be formalised in a variety of ways, leading to notions such as quasi(homo)morphisms and Ulam stability. Depending on the precise formulation of this problem, a whole different set of techniques, connections to other fields, and intriguing open problems reveals itself. I will give an overview of these problems, and talk about recent developments, including joint works with Sami Douba, Sam Hughes, Simon Machado, Bharatram Rangarajan and Rufus Willett.