GRACE: Gradient-guided Coreset Selection for LLM Unlearning

Praveen Bushipaka, Andrea D’Angelo, Lucia Passaro, Tommaso Cucinotta


Abstract
Machine Unlearning methods for Large Language Models typically assume pre-specified forget and retain sets. In realistic settings, however, requests may provide only a few examples of undesired behaviour, requiring forget and retain sets to be inferred from heterogeneous corpora. We study this data-selection problem and propose GRACE, a gradient-guided coreset selection method that constructs both forget and retain sets for LLM unlearning. GRACE first computes a forget direction from seed examples that elicit the undesired behaviour, then selects a compact forget coreset whose gradients approximate this direction using non-negative orthogonal matching pursuit. To preserve model utility, it selects retain examples after projecting out the forget direction and applying clustered orthogonal matching pursuit in the remaining gradient space. Across two target domains, two model families, and four unlearning algorithms, GRACE improves model utility while maintaining comparable forget quality, with particularly consistent gains over prior gradient-based selection methods.
Anthology ID:
2026.findings-emnlp.1212
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
25601–25620
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1212/
DOI:
Bibkey:
Cite (ACL):
Praveen Bushipaka, Andrea D’Angelo, Lucia Passaro, and Tommaso Cucinotta. 2026. GRACE: Gradient-guided Coreset Selection for LLM Unlearning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 25601–25620, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
GRACE: Gradient-guided Coreset Selection for LLM Unlearning (Bushipaka et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1212.pdf