arXiv Statistics ML

Certifiably Correct Fr\'echet Means in Orbit Spaces

The paper investigates Fréchet means in orbit spaces arising from finite orthogonal group actions, a problem known to be NP-hard. It introduces spectral and semidefinite relaxations inspired by group synchronization, and provides a semidefinite certificate that can certify global optimality even when pairwise alignment fails. The authors demonstrate the effectiveness of their methods on Gaussian data with sign ambiguity and through numerical experiments on districting plan ensembles and time‑series clustering.

arXiv Machine Learning
Oct 28

The Clustering Occupation Kernel (CLOCK) Method for Time Series Arising from Dynamical Systems

The paper introduces the Clustering Occupation Kernel (CLOCK) method, a representation-based framework that embeds time series from dynamical systems into a reproducing kernel Hilbert space using a time‑averaged occupation kernel. This embedding allows trajectory comparison via the RKHS norm and, for differential equation systems, approximates the kernel mean embedding of the invariant Sinai‑Ruelle‑Bowen measure, effectively measuring the maximum mean discrepancy between attractors. CLOCK handles unequal‑length and irregularly‑spaced data, incorporates Takens’ embedding for general time series, and demonstrates superior performance over benchmark methods on synthetic data and real intracranial EEG recordings, with ablation studies confirming theoretical convergence and noise robustness.

By Michael L. Wells, Kamel Lahouel, Victor Rielly, Bruno Jedynak
arXiv Machine Learning
Jul 13

Group Invariant Spectral Embedding

arXiv:2607. 08987v1 Announce Type: new Abstract: Spectral embedding methods are widely used for dimensionality reduction and clustering of high-dimensional datasets with intrinsic low-dimensional structures.

By Yeari Vigder, Paulina Hoyos, David Thong, Joakim and\'en, Joe Kileel, Amit Moscovich
arXiv Statistics ML
Sep 11

A Mean Field Games Perspective on Evolutionary Clustering

The paper introduces a control‑theoretic framework for evolutionary clustering using quasi‑stationary Mean Field Games. Each cluster is modeled as a probability density whose dynamics follow a Fokker–Planck equation, while a stationary Hamilton–Jacobi equation determines the velocity field. In a Gaussian specialization, affine dynamics replicate the mean and covariance trajectories of the classical Expectation–Maximization algorithm, and the authors propose causal and non‑causal time‑averaged log‑likelihood objectives to enhance temporal coherence, along with a fully density‑based numerical implementation for non‑Gaussian components. The method is evaluated on synthetic and real time‑dependent datasets, compared to snapshot Expectation–Maximization, temporally smoothed observations, and an evolutionary k‑means baseline.

By Alessio Basti, Fabio Camilli, Adriano Festa