Séminaire Jeunes chercheurs (Clarisse Boinay, jeudi 27 novembre 2025)

La prochaine séance du séminaire Jeunes chercheurs du CEREMADE aura lieu le jeudi 27 novembre 2025 à 17h en salle A707. Nous aurons le plaisir d'écouter Clarisse Boinay (INRIA), qui nous parlera de

Detection of anomalies in dynamic graphs with applications in cybersecurity for OT
 

Abstract
Aggregating instantaneous graphs can achieve approximate independence between the resulting aggregated graphs, a property supported by both (asymptotic) theoretical and (finite sample size) empirical evidence. This justifies the use of a multilayer Poisson-directed Stochastic Block Model (SBM) under the assumption of independence between layers. Within this unusual simplied framework for dynamic graphs, we propose a statistical test for anomaly detection. Furthermore, we extend the model to accommodate variations in the number of nodes over time by employing a missing data paradigm, overpassing in that way main litterature advances which are limited to the number of edges variations. Finally, we demonstrate that initializing the Variational Expectation-Maximization (VEM) algorithm using Singular Value Decomposition (SVD) is effective, even in the presence of missing data.