MAAT: Multi-phase Adapter-Aware Targeted Unlearning

Fuente: arXiv
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Main Authors: Yagnik, Suryash, Gaur, Shubham, Thakur, Saksham, Jain, Vinija, Chadha, Aman, Das, Amitava
Format: Preprint
Published: 2026
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author Yagnik, Suryash
Gaur, Shubham
Thakur, Saksham
Jain, Vinija
Chadha, Aman
Das, Amitava
author_facet Yagnik, Suryash
Gaur, Shubham
Thakur, Saksham
Jain, Vinija
Chadha, Aman
Das, Amitava
contents Machine unlearning evaluation is structurally skewed: Why-type questions, which probe causal and relational knowledge, comprise less than 0.06% of CounterFact, 0.6% of ZSRE, and less than 1.3% of TOFU, MUSE, and WMDP-Cyber. This near-zero representation means that methods that fail on causal knowledge can score highly in aggregate, and this failure is undetectable without balanced evaluation. We present 5WBENCH, a balanced 5,000-sample benchmark with 1,000 examples per 5W category (Who, What, When, Where, Why), making causal unlearning failures quantifiable for the first time. Using 5WBENCH, we show that no existing baseline simultaneously achieves high forgetting and high retention on Why-type questions: aggressive forgetting degrades retained knowledge, while conservative methods fail to forget causal facts. Why-type difficulty stems from multi-hop reasoning chains (44% of Why entries vs. less than or equal to 2% for others) and gradient dilution over 40.1-token answer spans. We present MAAT (Multi-phase Adapter-Aware Targeted Unlearning), a three-phase framework operating on LoRA adapter weights, combining gradient-projected ascent, SVD rank-dimension pruning, task vector negation, and hybrid KL-hidden-state retain repair. MAAT is the first method to simultaneously achieve high forgetting and high retention on Why-type causal knowledge, reaching a new operating point on the forget-retain Pareto frontier. We make our code publicly available.
format Preprint
id arxiv_https___arxiv_org_abs_2605_30514
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle MAAT: Multi-phase Adapter-Aware Targeted Unlearning
Yagnik, Suryash
Gaur, Shubham
Thakur, Saksham
Jain, Vinija
Chadha, Aman
Das, Amitava
Machine Learning
Computation and Language
Machine unlearning evaluation is structurally skewed: Why-type questions, which probe causal and relational knowledge, comprise less than 0.06% of CounterFact, 0.6% of ZSRE, and less than 1.3% of TOFU, MUSE, and WMDP-Cyber. This near-zero representation means that methods that fail on causal knowledge can score highly in aggregate, and this failure is undetectable without balanced evaluation. We present 5WBENCH, a balanced 5,000-sample benchmark with 1,000 examples per 5W category (Who, What, When, Where, Why), making causal unlearning failures quantifiable for the first time. Using 5WBENCH, we show that no existing baseline simultaneously achieves high forgetting and high retention on Why-type questions: aggressive forgetting degrades retained knowledge, while conservative methods fail to forget causal facts. Why-type difficulty stems from multi-hop reasoning chains (44% of Why entries vs. less than or equal to 2% for others) and gradient dilution over 40.1-token answer spans. We present MAAT (Multi-phase Adapter-Aware Targeted Unlearning), a three-phase framework operating on LoRA adapter weights, combining gradient-projected ascent, SVD rank-dimension pruning, task vector negation, and hybrid KL-hidden-state retain repair. MAAT is the first method to simultaneously achieve high forgetting and high retention on Why-type causal knowledge, reaching a new operating point on the forget-retain Pareto frontier. We make our code publicly available.
title MAAT: Multi-phase Adapter-Aware Targeted Unlearning
topic Machine Learning
Computation and Language
url https://arxiv.org/abs/2605.30514