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Main Authors: Ikram, Zarif, Firouzkouhi, Arad, Tu, Stephen, Soltanolkotabi, Mahdi, Rashidinejad, Paria
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2602.15823
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author Ikram, Zarif
Firouzkouhi, Arad
Tu, Stephen
Soltanolkotabi, Mahdi
Rashidinejad, Paria
author_facet Ikram, Zarif
Firouzkouhi, Arad
Tu, Stephen
Soltanolkotabi, Mahdi
Rashidinejad, Paria
contents A central challenge in large language model (LLM) editing is capability preservation: methods that successfully change targeted behavior can quietly game the editing proxy and corrupt general capabilities, producing degenerate behaviors reminiscent of proxy/reward hacking. We present CrispEdit, a scalable and principled second-order editing algorithm that treats capability preservation as an explicit constraint, unifying and generalizing several existing editing approaches. CrispEdit formulates editing as constrained optimization and enforces the constraint by projecting edit updates onto the low-curvature subspace of the capability-loss landscape. At the crux of CrispEdit is expressing capability constraint via Bregman divergence, whose quadratic form yields the Gauss-Newton Hessian exactly and even when the base model is not trained to convergence. We make this second-order procedure efficient at the LLM scale using Kronecker-factored approximate curvature (K-FAC) and a novel matrix-free projector that exploits Kronecker structure to avoid constructing massive projection matrices. Across standard model-editing benchmarks, CrispEdit achieves high edit success while keeping capability degradation below 1% on average across datasets, significantly improving over prior editors.
format Preprint
id arxiv_https___arxiv_org_abs_2602_15823
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle CrispEdit: Low-Curvature Projections for Scalable Non-Destructive LLM Editing
Ikram, Zarif
Firouzkouhi, Arad
Tu, Stephen
Soltanolkotabi, Mahdi
Rashidinejad, Paria
Machine Learning
Artificial Intelligence
A central challenge in large language model (LLM) editing is capability preservation: methods that successfully change targeted behavior can quietly game the editing proxy and corrupt general capabilities, producing degenerate behaviors reminiscent of proxy/reward hacking. We present CrispEdit, a scalable and principled second-order editing algorithm that treats capability preservation as an explicit constraint, unifying and generalizing several existing editing approaches. CrispEdit formulates editing as constrained optimization and enforces the constraint by projecting edit updates onto the low-curvature subspace of the capability-loss landscape. At the crux of CrispEdit is expressing capability constraint via Bregman divergence, whose quadratic form yields the Gauss-Newton Hessian exactly and even when the base model is not trained to convergence. We make this second-order procedure efficient at the LLM scale using Kronecker-factored approximate curvature (K-FAC) and a novel matrix-free projector that exploits Kronecker structure to avoid constructing massive projection matrices. Across standard model-editing benchmarks, CrispEdit achieves high edit success while keeping capability degradation below 1% on average across datasets, significantly improving over prior editors.
title CrispEdit: Low-Curvature Projections for Scalable Non-Destructive LLM Editing
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2602.15823