Bilinear autoencoders find interpretable manifolds

Fuente: arXiv
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Main Authors: Dooms, Thomas, Gauderis, Ward, Wiggins, Geraint, Oramas, Jose
Format: Preprint
Published: 2026
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author Dooms, Thomas
Gauderis, Ward
Wiggins, Geraint
Oramas, Jose
author_facet Dooms, Thomas
Gauderis, Ward
Wiggins, Geraint
Oramas, Jose
contents Sparse autoencoders have become a standard tool for uncovering interpretable latent representations in neural networks. Yet salient concepts often span manifolds that current linear methods cannot capture without post hoc analysis. This paper uses quadratic latents to close this gap: we implement these with bilinear autoencoders, which decompose activations into low-rank quadratic forms, compose linearly in weight space, and admit input-independent geometric analysis. This qualitative difference in what concepts quadratic latents can detect challenges the standard linear representation hypothesis. Our experiments and visualisations show that multi-dimensional geometries are highly prevalent and that composite latents capture them well, systematically improving reconstruction error in language models. Furthermore, we show that autoencoders with varying geometric priors recover the same input subspace despite their dictionary entries being distinct. Practically, these models serve as an unsupervised tool for manifold discovery, which we demonstrate through an interactive online visualizer for Qwen 3.5. This is a step toward nonlinear but mathematically tractable latent representations whose composition is expressive and interpretable by design.
format Preprint
id arxiv_https___arxiv_org_abs_2605_08891
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Bilinear autoencoders find interpretable manifolds
Dooms, Thomas
Gauderis, Ward
Wiggins, Geraint
Oramas, Jose
Machine Learning
Sparse autoencoders have become a standard tool for uncovering interpretable latent representations in neural networks. Yet salient concepts often span manifolds that current linear methods cannot capture without post hoc analysis. This paper uses quadratic latents to close this gap: we implement these with bilinear autoencoders, which decompose activations into low-rank quadratic forms, compose linearly in weight space, and admit input-independent geometric analysis. This qualitative difference in what concepts quadratic latents can detect challenges the standard linear representation hypothesis. Our experiments and visualisations show that multi-dimensional geometries are highly prevalent and that composite latents capture them well, systematically improving reconstruction error in language models. Furthermore, we show that autoencoders with varying geometric priors recover the same input subspace despite their dictionary entries being distinct. Practically, these models serve as an unsupervised tool for manifold discovery, which we demonstrate through an interactive online visualizer for Qwen 3.5. This is a step toward nonlinear but mathematically tractable latent representations whose composition is expressive and interpretable by design.
title Bilinear autoencoders find interpretable manifolds
topic Machine Learning
url https://arxiv.org/abs/2605.08891