In this talk, we consider a simple random walk defined on a Chung-Lu directed graph, an inhomogeneous random network that extends the Erdos Renyi random digraph by including edges independently according to given Bernoulli laws. In this non-reversible setting, we will focus on the convergence toward the equilibrium of the dynamics. In particular, under the assumption that the average degree grows logarithmically in the size n of the graph (weakly dense regime), we will establish a cutoff phenomenon at the entropic time of order log(n)/loglog(n). We will then show that on a precise window the cutoff profile converges to the Gaussian tail function. This is qualitatively similar to what was proved in a series of works by Bordenave, Caputo, Salez for the directed configuration model, where degrees are deterministically fixed. In terms of statistical ensembles, this analysis provides an extension of these cutoff results from a hard to a soft-constrained model. Joint work with G. Passuello.

In 2020, a group of theoretical computer scientists posted a paper on the Arxiv with the strange-looking title "MIP* = RE", impacting and surprising not only complexity theory but also some areas of math and physics. Specifically, it resolved, in the negative, the "Connes' embedding conjecture" in the area of von-Neumann algebras, and the "Tsirelson problem" in quantum information theory. You can find the paper here. As it happens, both acronyms MIP* and RE represent proof systems, of a very different nature. To explain them, we'll take a meandering journey through the classical and modern definitions of proof. I hope to explain how the methodology of computational complexity theory, especially modeling and classification (both problems and proofs) by algorithmic efficiency, naturally leads to the generation of new such notions and results (and more acronyms, like NP). A special focus will be on notions of proof which allow interaction, randomness, and errors, and their surprising power and magical properties, including ZK (Zero Knowledge proofs) and PCPs (Probababilistically Checkable Proofs). The talk will be non-technical, and requires no special background.