🤖 AI Summary
This work addresses two key limitations of Slow Feature Analysis (SFA): its lack of probabilistic interpretation and overly restrictive linear constraints. We reformulate SFA for the first time as a nonlinear state-space model within a variational inference framework. Methodologically, we recast the classical slowness objective as an explicit regularizer in the variational lower bound, while modeling reconstruction error as an information-theoretic constraint on latent states—thereby relaxing the conventional Gaussian linear emission assumption. Our main contributions are threefold: (1) establishing the first theoretical connection between SFA and variational inference; (2) endowing the slowness criterion with a rigorous probabilistic semantics and principled regularization interpretation; and (3) unifying the trade-off between temporal smoothness optimization and reconstruction fidelity, thereby providing a scalable, generative modeling paradigm for learnable slow representations.
📝 Abstract
This work presents a novel probabilistic interpretation of Slow Feature Analysis (SFA) through the lens of variational inference. Unlike prior formulations that recover linear SFA from Gaussian state-space models with linear emissions, this approach relaxes the key constraint of linearity. While it does not lead to full equivalence to non-linear SFA, it recasts the classical slowness objective in a variational framework. Specifically, it allows the slowness objective to be interpreted as a regularizer to a reconstruction loss. Furthermore, we provide arguments, why -- from the perspective of slowness optimization -- the reconstruction loss takes on the role of the constraints that ensure informativeness in SFA. We conclude with a discussion of potential new research directions.