Toeplitz MLP Mixers are Low Complexity, Information-Rich Sequence Models

Fuente: arXiv
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Hauptverfasser: Badger, Benjamin L., Roland, Ethan
Format: Preprint
Veröffentlicht: 2026
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author Badger, Benjamin L.
Roland, Ethan
author_facet Badger, Benjamin L.
Roland, Ethan
contents Transformer-based large language models are in some respects limited by the quadratic time and space computational complexity of attention. We introduce the Toeplitz MLP Mixer (TMM), a transformer-like architecture that swaps attention for triangular-masked Toeplitz matrix multiplication over the sequence dimension resulting in $\mathcal{O} (dn \log n)$ time and $\mathcal O(dn)$ space complexity during training and $\mathcal O(dn)$ time and space at inference prefill. Despite the lack of sophisticated input modulation or state maintenance present in other sub-quadratic architectures, TMMs yield greater training efficiency in terms of loss achieved per compute and device memory. We demonstrate that TMMs are capable of retaining more input information resulting in improved copying ability, which we argue results from a lack of architectural biases. Consistent with higher input information retention, TMMs exhibit superior information retrieval and in-context learning benchmark accuracy compared to comparable architectures. We conclude with an analysis from the perspective of operator index theory and show that, counterintuitively, trained Toeplitz layers of causal non-invertible models are more likely to be invertible or nearly so than models that are actually invertible over their inputs.
format Preprint
id arxiv_https___arxiv_org_abs_2605_06683
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Toeplitz MLP Mixers are Low Complexity, Information-Rich Sequence Models
Badger, Benjamin L.
Roland, Ethan
Machine Learning
Artificial Intelligence
Computation and Language
Transformer-based large language models are in some respects limited by the quadratic time and space computational complexity of attention. We introduce the Toeplitz MLP Mixer (TMM), a transformer-like architecture that swaps attention for triangular-masked Toeplitz matrix multiplication over the sequence dimension resulting in $\mathcal{O} (dn \log n)$ time and $\mathcal O(dn)$ space complexity during training and $\mathcal O(dn)$ time and space at inference prefill. Despite the lack of sophisticated input modulation or state maintenance present in other sub-quadratic architectures, TMMs yield greater training efficiency in terms of loss achieved per compute and device memory. We demonstrate that TMMs are capable of retaining more input information resulting in improved copying ability, which we argue results from a lack of architectural biases. Consistent with higher input information retention, TMMs exhibit superior information retrieval and in-context learning benchmark accuracy compared to comparable architectures. We conclude with an analysis from the perspective of operator index theory and show that, counterintuitively, trained Toeplitz layers of causal non-invertible models are more likely to be invertible or nearly so than models that are actually invertible over their inputs.
title Toeplitz MLP Mixers are Low Complexity, Information-Rich Sequence Models
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2605.06683