SFAL: Semantic-Functional Alignment Scores for Distributional Evaluation of Auto-Interpretability in Sparse Autoencoders

Fabio Mercorio, Filippo Pallucchini, Daniele Potertì, Antonio Serino, Andrea Seveso


Abstract
Interpreting the internal representations of large language models (LLMs) is crucial for their deployment in real-world applications, impacting areas such as AI safety, debugging, and compliance. Sparse Autoencoders facilitate interpretability by decomposing polysemantic activation into a latent space of monosemantic features. However, evaluating the auto-interpretability of these features is difficult and computationally expensive, which limits scalability in practical settings. In this work, we propose SFAL, an alternative evaluation strategy that reduces reliance on LLM-based scoring by assessing the alignment between the semantic neighbourhoods of features (derived from auto-interpretation embeddings) and their functional neighbourhoods (derived from co-occurrence statistics).Our method enhances efficiency, enabling fast and cost-effective assessments. We validate our approach on large-scale models, demonstrating its potential to provide interpretability while reducing computational overhead, making it suitable for real-world deployment.
Anthology ID:
2025.emnlp-industry.39
Volume:
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
November
Year:
2025
Address:
Suzhou (China)
Editors:
Saloni Potdar, Lina Rojas-Barahona, Sebastien Montella
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
576–583
Language:
URL:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-industry.39/
DOI:
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Cite (ACL):
Fabio Mercorio, Filippo Pallucchini, Daniele Potertì, Antonio Serino, and Andrea Seveso. 2025. SFAL: Semantic-Functional Alignment Scores for Distributional Evaluation of Auto-Interpretability in Sparse Autoencoders. In Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 576–583, Suzhou (China). Association for Computational Linguistics.
Cite (Informal):
SFAL: Semantic-Functional Alignment Scores for Distributional Evaluation of Auto-Interpretability in Sparse Autoencoders (Mercorio et al., EMNLP 2025)
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https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-industry.39.pdf