Understanding LLMs' Cross-Lingual Context Retrieval: How Good It Is And Where It Comes From

Fuente: arXiv
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Main Authors: Gao, Changjiang, Lin, Hankun, Huang, Xin, Han, Xue, Feng, Junlan, Deng, Chao, Chen, Jiajun, Huang, Shujian
Format: Preprint
Published: 2025
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author Gao, Changjiang
Lin, Hankun
Huang, Xin
Han, Xue
Feng, Junlan
Deng, Chao
Chen, Jiajun
Huang, Shujian
author_facet Gao, Changjiang
Lin, Hankun
Huang, Xin
Han, Xue
Feng, Junlan
Deng, Chao
Chen, Jiajun
Huang, Shujian
contents Cross-lingual context retrieval (extracting contextual information in one language based on requests in another) is a fundamental aspect of cross-lingual alignment, but the performance and mechanism of it for large language models (LLMs) remains unclear. In this paper, we evaluate the cross-lingual context retrieval of over 40 LLMs across 12 languages, using cross-lingual machine reading comprehension (xMRC) as a representative scenario. Our results show that post-trained open LLMs show strong cross-lingual context retrieval ability, comparable to closed-source LLMs such as GPT-4o, and their estimated oracle performances greatly improve after post-training. Our mechanism analysis shows that the cross-lingual context retrieval process can be divided into two main phases: question encoding and answer retrieval, which are formed in pre-training and post-training respectively. The phasing stability correlates with xMRC performance, and the xMRC bottleneck lies at the last model layers in the second phase, where the effect of post-training can be evidently observed. Our results also indicate that larger-scale pretraining cannot improve the xMRC performance. Instead, larger LLMs need further multilingual post-training to fully unlock their cross-lingual context retrieval potential.
format Preprint
id arxiv_https___arxiv_org_abs_2504_10906
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Understanding LLMs' Cross-Lingual Context Retrieval: How Good It Is And Where It Comes From
Gao, Changjiang
Lin, Hankun
Huang, Xin
Han, Xue
Feng, Junlan
Deng, Chao
Chen, Jiajun
Huang, Shujian
Computation and Language
Cross-lingual context retrieval (extracting contextual information in one language based on requests in another) is a fundamental aspect of cross-lingual alignment, but the performance and mechanism of it for large language models (LLMs) remains unclear. In this paper, we evaluate the cross-lingual context retrieval of over 40 LLMs across 12 languages, using cross-lingual machine reading comprehension (xMRC) as a representative scenario. Our results show that post-trained open LLMs show strong cross-lingual context retrieval ability, comparable to closed-source LLMs such as GPT-4o, and their estimated oracle performances greatly improve after post-training. Our mechanism analysis shows that the cross-lingual context retrieval process can be divided into two main phases: question encoding and answer retrieval, which are formed in pre-training and post-training respectively. The phasing stability correlates with xMRC performance, and the xMRC bottleneck lies at the last model layers in the second phase, where the effect of post-training can be evidently observed. Our results also indicate that larger-scale pretraining cannot improve the xMRC performance. Instead, larger LLMs need further multilingual post-training to fully unlock their cross-lingual context retrieval potential.
title Understanding LLMs' Cross-Lingual Context Retrieval: How Good It Is And Where It Comes From
topic Computation and Language
url https://arxiv.org/abs/2504.10906