PRISM: Refracting Large-Batch Model Editing through Jacobian-Inferred FFN Subspaces

Ziyue Zhai, Qiyao Liu, Hao Song, Heng Yu, Guozhi Lin, Yulai Yang, Xuan Zhang


Abstract
Model editing updates factual knowledge in large language models (LLMs) without retraining, but simultaneous large-batch edits can degrade generalization and locality as edit interactions accumulate. We study this problem through a multi-scale analysis of feed-forward network (FFN) and multi-head self-attention (MHSA) geometry. Weak FFN–MHSA token-level alignment can coexist with non-trivial distributional coupling, while Jacobian-inferred FFN local-response geometry provides a distinct proxy for locally supported response directions. Based on this distinction, we propose PRISM, which replaces unconstrained residual-target fitting with controlled residual correction within edit-conditioned, Jacobian-inferred local-response subspaces. On the standard CounterFact large-batch benchmark, improves the baseline’s Score by 1.3–1.7 points and Generalization by 1.7–1.8 points at 10k edits, with larger Generalization gains in beyond-10k scaling tests at 20k edits while maintaining competitive Specificity.
Anthology ID:
2026.emnlp-main.997
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
22931–22949
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URL:
https://aclanthology.org/2026.emnlp-main.997/
DOI:
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Cite (ACL):
Ziyue Zhai, Qiyao Liu, Hao Song, Heng Yu, Guozhi Lin, Yulai Yang, and Xuan Zhang. 2026. PRISM: Refracting Large-Batch Model Editing through Jacobian-Inferred FFN Subspaces. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 22931–22949, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
PRISM: Refracting Large-Batch Model Editing through Jacobian-Inferred FFN Subspaces (Zhai et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.997.pdf