Evaluating Cross-Lingual Unlearning in Multilingual Language Models

Fuente: arXiv
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Autori principali: Lizzo, Tyler, Heck, Larry
Natura: Preprint
Pubblicazione: 2026
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author Lizzo, Tyler
Heck, Larry
author_facet Lizzo, Tyler
Heck, Larry
contents We present the first comprehensive evaluation of cross-lingual unlearning in multilingual LLMs. Using translated TOFU benchmarks in seven language/script variants, we test major unlearning algorithms and show that most fail to remove facts outside the training language, even when utility remains high. However, subspace-projection consistently outperforms the other methods, achieving strong cross-lingual forgetting with minimal degradation. Analysis of learned task subspaces reveals a shared interlingua structure: removing this shared subspace harms all languages, while removing language-specific components selectively affects one. These results demonstrate that multilingual forgetting depends on geometry in weight space, motivating subspace-based approaches for future unlearning systems.
format Preprint
id arxiv_https___arxiv_org_abs_2601_06675
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Evaluating Cross-Lingual Unlearning in Multilingual Language Models
Lizzo, Tyler
Heck, Larry
Computation and Language
We present the first comprehensive evaluation of cross-lingual unlearning in multilingual LLMs. Using translated TOFU benchmarks in seven language/script variants, we test major unlearning algorithms and show that most fail to remove facts outside the training language, even when utility remains high. However, subspace-projection consistently outperforms the other methods, achieving strong cross-lingual forgetting with minimal degradation. Analysis of learned task subspaces reveals a shared interlingua structure: removing this shared subspace harms all languages, while removing language-specific components selectively affects one. These results demonstrate that multilingual forgetting depends on geometry in weight space, motivating subspace-based approaches for future unlearning systems.
title Evaluating Cross-Lingual Unlearning in Multilingual Language Models
topic Computation and Language
url https://arxiv.org/abs/2601.06675