Compressed Sensing for Capability Localization in Large Language Models

Fuente: arXiv
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Autori principali: Bair, Anna, Xu, Yixuan Even, Sun, Mingjie, Kolter, J. Zico
Natura: Preprint
Pubblicazione: 2026
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author Bair, Anna
Xu, Yixuan Even
Sun, Mingjie
Kolter, J. Zico
author_facet Bair, Anna
Xu, Yixuan Even
Sun, Mingjie
Kolter, J. Zico
contents Large language models (LLMs) exhibit a wide range of capabilities, including mathematical reasoning, code generation, and linguistic behaviors. We show that many capabilities are highly localized to small subsets of attention heads within Transformer architectures. Zeroing out as few as five task-specific heads can degrade performance by up to $65\%$ on standard benchmarks measuring the capability of interest, while largely preserving performance on unrelated tasks. We introduce a compressed sensing based method that exploits the sparsity of these heads to identify them via strategic knockouts and a small number of model evaluations. We validate these findings across Llama and Qwen models ranging from 1B to 8B parameters and a diverse set of capabilities including mathematical abilities and code generation, revealing a modular organization in which specialized capabilities are implemented by sparse, functionally distinct components. Overall, our results suggest that capability localization is a general organizational principle of Transformer language models, with implications for interpretability, model editing, and AI safety. Code is released at https://github.com/locuslab/llm-components.
format Preprint
id arxiv_https___arxiv_org_abs_2603_03335
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Compressed Sensing for Capability Localization in Large Language Models
Bair, Anna
Xu, Yixuan Even
Sun, Mingjie
Kolter, J. Zico
Computation and Language
Large language models (LLMs) exhibit a wide range of capabilities, including mathematical reasoning, code generation, and linguistic behaviors. We show that many capabilities are highly localized to small subsets of attention heads within Transformer architectures. Zeroing out as few as five task-specific heads can degrade performance by up to $65\%$ on standard benchmarks measuring the capability of interest, while largely preserving performance on unrelated tasks. We introduce a compressed sensing based method that exploits the sparsity of these heads to identify them via strategic knockouts and a small number of model evaluations. We validate these findings across Llama and Qwen models ranging from 1B to 8B parameters and a diverse set of capabilities including mathematical abilities and code generation, revealing a modular organization in which specialized capabilities are implemented by sparse, functionally distinct components. Overall, our results suggest that capability localization is a general organizational principle of Transformer language models, with implications for interpretability, model editing, and AI safety. Code is released at https://github.com/locuslab/llm-components.
title Compressed Sensing for Capability Localization in Large Language Models
topic Computation and Language
url https://arxiv.org/abs/2603.03335