Mechanism-Guided Selective Unlearning for RLVR-Induced Reasoning
On the map: LLM safety and security → Machine unlearning
Abstract (arXiv)
We propose MAST (Mechanism-Aligned Selective Targeting), a mechanism-guided method for unlearning RLVR-induced reasoning with substantially lower collateral damage than standard full-parameter updates. In matched SFT/RLVR checkpoints on Qwen2.5-Math-1.5B and Qwen3-1.7B-Base, the SFT-to-RLVR increment differs sharply from the SFT update in token-level delta-log-probability, and full-parameter gradient ascent forgets only by damaging retain MATH and GSM8K. MAST ranks attention-projection tensors by off-principal energy, update magnitude, and forget-gradient coupling magnitude, then updates only the top-ranked subset. On the primary model, MAST induces statistically significant target forgetting (MATH forget 45/150 to 37/150; McNemar p=0.0078) while preserving GSM8K (+0.8 pp) and MATH retain (-0.5 pp). The advantage reproduces across seeds, NPO/SimNPO objectives, and Qwen3, where MAST preserves GSM8K while full-parameter unlearning collapses it.
Key facts. No citing papers in the map yet (data through 14 Oct 2026). Placed in Machine unlearning, one of 12 directions in LLM safety and security. Builds on 16 of its 17 references that are in the map. First posted on arXiv 17 Jun 2026.
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Other references · 11
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- 2024The WMDP Benchmark: Measuring and Reducing Malicious Use With Unlearningcited by 509
- 2023Does Localization Inform Editing? Surprising Differences in Causality-Based Localization vs. Knowledge Editing in Language Modelscited by 243
- 2025The Path Not Taken: RLVR Provably Learns Off the Principalscited by 56
- 2026On the Direction of RLVR Updates for LLM Reasoning: Identification and Exploitationcited by 13
- 2026GeoRA: Geometry-Aware Low-Rank Adaptation for RLVRcited by 4
- 2026Delta-Crosscoder: Robust Crosscoder Model Diffing in Narrow Fine-Tuning Regimescited by 4
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