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arXiv · 2511.20910

Emergence and Localisation of Semantic Role Circuits in LLMs

Nura Aljaafari·Danilo S. Carvalho·André Freitas
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Abstract

Despite displaying semantic competence, large language models' internal mechanisms that ground abstract semantic structure remain insufficiently characterised. We propose a method integrating role-cross minimal pairs, temporal emergence analysis, and cross-model comparison to study how LLMs implement semantic roles. Our analysis uncovers: (i) highly concentrated circuits (89-94% attribution within 28 nodes); (ii) gradual structural refinement rather than phase transitions, with larger models sometimes bypassing localised circuits; and (iii) moderate cross-scale conservation (24-59% component overlap) alongside high spectral similarity. These findings suggest that LLMs form compact, causally isolated mechanisms for abstract semantic structure, and these mechanisms exhibit partial transfer across scales and architectures.

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Nura Aljaafari, Danilo S. Carvalho, André Freitas. 2025-11-25. Emergence and Localisation of Semantic Role Circuits in LLMs. https://arxiv.org/abs/2511.20910

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