Transient anisotropic kernel for probabilistic learning on manifolds

TL;DR

This paper introduces a transient anisotropic kernel for probabilistic learning on manifolds, enhancing the representation of statistical dependencies in small, heterogeneous datasets by improving the basis used in PLoM.

Contribution

It proposes a new transient anisotropic kernel basis for PLoM, which better captures data heterogeneity and improves probabilistic surrogate modeling.

Findings

Transient basis aligns with DMAPS basis at initial times.

Improved statistical dependency representation in learned measures.

Validated through three diverse application examples.

Abstract

PLoM (Probabilistic Learning on Manifolds) is a method introduced in 2016 for handling small training datasets by projecting an It\^o equation from a stochastic dissipative Hamiltonian dynamical system, acting as the MCMC generator, for which the KDE-estimated probability measure with the training dataset is the invariant measure. PLoM performs a projection on a reduced-order vector basis related to the training dataset, using the diffusion maps (DMAPS) basis constructed with a time-independent isotropic kernel. In this paper, we propose a new ISDE projection vector basis built from a transient anisotropic kernel, providing an alternative to the DMAPS basis to improve statistical surrogates for stochastic manifolds with heterogeneous data. The construction ensures that for times near the initial time, the DMAPS basis coincides with the transient basis. For larger times, the differences between the two bases are characterized by the angle of their spanned vector subspaces. The optimal instant yielding the optimal transient basis is determined using an estimation of mutual information from Information Theory, which is normalized by the entropy estimation to account for the effects of the number of realizations used in the estimations. Consequently, this new vector basis better represents statistical dependencies in the learned probability measure for any dimension. Three applications with varying levels of statistical complexity and data heterogeneity validate the proposed theory, showing that the transient anisotropic kernel improves the learned probability measure.