Saved in:
| Main Authors: | , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | https://arxiv.org/abs/2504.10645 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Table of Contents:
- In this article, we explore Bayesian extensions of the tensor normal model through a geometric expansion of the multi-way covariance's Cholesky factor inspired by the Fréchet mean under the log-Cholesky metric. Specifically, within a tensor normal framework, we identify three structural components in the covariance of the vectorized data. By parameterizing vector normal covariances through such a Cholesky factor representation, analogous to a finite average of multiway Cholesky factors, we eliminate one of these structural components without compromising the analytical tractability of the likelihood, in which the multiway covariance is a special case. Furthermore, we demonstrate that a specific class of structured Cholesky factors can be precisely represented under this parameterization, serving as an analogue to the Pitsianis-Van Loan decomposition. We apply this model using Hamiltonian Monte Carlo in a fixed-mean setting for two-way covariance relevancy detection of components, where efficient analytical gradient updates are available, as well as in a seasonally-varying covariance process regime.