ICM 2026 Invited Section Lecture - Judith Rousseau

ICM 2026 Invited Section Lecture - Judith Rousseau

🎙 Judith Rousseau 👥 61K 📅 September 28, 2026 ⏱ 32 min 👁 192 📄 original study 🧭 2026-10-06
Available in: English (current) Français

Keywords

Hawkes processBayesianhigh-dimensionalposterior contractionsparsity

Summary

The lecture presents theoretical results on Bayesian estimation in high-dimensional linear Hawkes processes. The setting involves multiple point processes (e.g., neuronal spike trains) where interactions are modeled via intensity functions. The focus is on recovering the sparse interaction graph and associated parameters. The speaker introduces a hierarchical prior that selects the number of nonzero interaction functions for each component, leading to a posterior that factorizes across neurons. Two loss functions are considered: empirical L1 distance on intensities and L1 norm on parameters. The main contributions are posterior contraction rates for both metrics when the dimension grows with time, under mild sparsity and stationarity assumptions. Results show that for intensity estimation, the rate is near oracle ; for parameter estimation, an exponential complexity term appears unless the prior enforces strong sparsity via light tails on the number of nonzero functions. The lecture highlights the difficulty of estimating parameters directly and contrasts with importance of prior choice, comparing selection priors with spike-and-slab priors. Numerical examples indicate practical feasibility. The talk concludes by explaining why the L1 parameter rate is harder, due to the need to isolate each component in intervals with no events.

191 words

Critical Evaluation

Value of the Information & Strength of the Argument

The value of the information is substantial: it presents novel theoretical guarantees for Bayesian procedures in a high-dimensional setting that was previously only studied for fixed dimension. The argumentation is rigorous, built on probabilistic inequalities and careful control of posterior concentrations. The speaker clearly explains the assumptions and their role, and the proof outlines are given for the main results. The distinction between estimating intensities and parameters is well-motivated, and the discussion on prior elicitation provides practical guidance. The argumentation would benefit from more explicit comparisons with existing frequentist methods and a more detailed explanation of the technical conditions, but overall it is compelling and technically sound.

Scientific Rigor, Source Quality, Title Accuracy

The lecture is based on a specific research paper (implied) and refers to prior work by the author and others. The sources are not explicitly listed with URLs, but the speaker mentions relevant literature (e.g., Hansen et al. for frequentist lasso methods). The title is perfectly aligned with the content. The presentation is rigorous, with clear definitions and theorem statements. The lack of a formal reference list is a limitation, but the talk is intended as an expert-level lecture, not a literature review. The adequacy between title and content is excellent.

213 words

Title / Content Match

Title accurately describes the content: Bayesian estimation in linear high-dimensional Hawkes processes.

Quality & Reliability

8/10

Lecture by a leading statistician presenting original peer-reviewed research; rigorous mathematical arguments, explicit model assumptions, and clear statements of results.

Key Moments

Cited Sources

  • Estimation in Linear High Dimensional Hawkes Processes: A Bayesian Approach — Main paper referenced in the description, presenting the work discussed in the lecture.
  • Hansen et al. (frequentist lasso for Hawkes processes) — Mentioned as foundational work on multivariate Hawkes processes for finite dimension.

Concurring Sources

  • Hansen et al. (frequentist lasso for Hawkes processes) — Provides the frequentist counterpart and motivates the Bayesian approach.

Contribution & Novelties

The lecture provides original theoretical contributions to Bayesian inference for high-dimensional Hawkes processes, a setting that had not been previously addressed. The key novelty is the derivation of posterior contraction rates under sparsity, allowing the dimension K to grow nearly exponentially with time. The hierarchical selection prior is shown to be superior to standard spike-and-slab priors in achieving good rates. The separation between intensity estimation and parameter estimation highlights a fundamental challenge and explains when exponential penalties arise.

Pour aller plus loin :

114 words

Radar Profile

The profile shows high technical level and strong information quality, with slightly lower scores on quantity of information and overall reliability due to the niche nature and lack of explicit citations. The lecture is dense but well-structured.

Reliability 8/10