arXiv Machine Learning

On attention heads and bilinear forms

The paper investigates the symmetric and antisymmetric components of bilinear forms that arise in the attention heads of large language models. It introduces an orthogonally invariant profile map that projects real bilinear forms onto a three‑dimensional simplex, revealing that the profiles of trained bilinear forms tend to cluster near those of rank‑one bilinear forms. Additionally, the authors prove that for a Zariski‑dense subset of query‑key matrices, the symmetric part of a bilinear form in an attention head can be decomposed into a hyperbolic form plus a zero form.

arXiv Computation and Language
Oct 5

Emergent Structure in the Marginal Attention Space of Language Models

The paper investigates how post‑softmax attention weights behave across different language models by marginalizing over query positions to create a joint token‑head space. Across more than 60 diverse LLMs, token‑wise marginal attention reveals a text‑intrinsic signal that is conserved across models, while head‑wise marginal attention yields a model‑private signature that is consistent across documents. This insight enables a practical method for estimating per‑head budgets for key‑value cache eviction, achieving competitive performance on standard benchmarks without per‑document recomputation or training.

By Valentino Maiorca, Walter Nelson, Francesco Locatello
arXiv Machine Learning
Oct 16

Inherent Trade-offs when Enforcing Correct Data Symmetries in Multi-head Self-attention

arXiv:2608. 30417v2 Announce Type: replace Abstract: We give a complete characterization of equivariant multi-head self-attention (MHSA): if an MHSA layer is equivariant to a symmetry group $G$, then $G$ can only act by permuting head-clusters, with QK and OV matrices satisfying an equivariance constraint tied to the group action.

By T\=ikun \^Ong, Georg B\"okman
arXiv Machine Learning
Sep 30

On State Reduction in Linear Attention

arXiv:2602.04852v3 Announce Type: replace Abstract: Linear attention offers a computationally efficient yet expressive alternative to softmax attention. However, recent empirical results indicate tha...

By Philipp Nazari, T. Konstantin Rusch
arXiv Machine Learning
Sep 4

High-Dimensional Learning Dynamics of Attention-Indexed Models

The paper investigates the training dynamics of attention mechanisms in high-dimensional settings, focusing on attention-indexed models that encompass multi-layer and multi-head architectures. It shows that while the loss landscape can be described by a finite set of trace order parameters, the online stochastic gradient descent dynamics involve an infinite hierarchy of matrix moments that can be accurately approximated by a finite truncated system. The study further reveals that the choice of attention parameterization acts as an implicit bias: untied attention can get trapped in uninformative states, whereas tied attention induces symmetry breaking and enables weak recovery with θ(d² log d) samples, and untied attention exhibits a fast-slow dynamic leading to weak recovery when symmetry is broken.

By Yizhou Xu, Margarita Sagitova, Lenka Zdeborov\'a, Florent Krzakala
arXiv Machine Learning
Jul 1

Symmetry in language statistics shapes the geometry of model representations

arXiv:2602. 15029v3 Announce Type: replace Abstract: The internal representations learned by language models consistently exhibit striking geometric structure: calendar months organize into a circle, historical years form a smooth one-dimensional manifold, and cities' latitudes and longitudes can be decoded using a linear probe.

By Dhruva Karkada, Daniel J. Korchinski, Andres Nava, Matthieu Wyart, Yasaman Bahri
arXiv AI
Oct 12

Not All Dimensions Are Equal: Outlier-Aware Attention Linearization with Grouped Quadratic Kernels

The paper introduces Outlier-Aware Attention Linearization (OAL), a method that improves linearized softmax attention by explicitly accounting for a few outlier dimensions that disproportionately affect query-key dot products. OAL builds on a second-order Taylor approximation, uses a Hadamard-product formulation to expose dimension-specific contributions, and groups dimensions with similar scales to share coefficients while treating outliers separately. Experiments on Qwen2.5-0.5B show an 8.9% reduction in frozen-attention output MSE, and fine-tuning with LoRA lowers WikiText-103 perplexity from 31.71 to 27.50 while boosting performance on PIQA, HellaSwag, and ARC-E.

By Weiqi Sun, Qianyue Wu, Wenjia Wang, Tianyang Hu