Overcoming Vocabulary Mismatch: Vocabulary-agnostic Teacher Guided Language Modeling

Fuente: arXiv
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Auteurs principaux: Shin, Haebin, Ji, Lei, Liu, Xiao, Gong, Yeyun
Format: Preprint
Publié: 2025
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author Shin, Haebin
Ji, Lei
Liu, Xiao
Gong, Yeyun
author_facet Shin, Haebin
Ji, Lei
Liu, Xiao
Gong, Yeyun
contents Using large teacher models to guide the training of smaller student models has become the prevailing paradigm for efficient and effective learning. However, vocabulary mismatches between teacher and student language models pose significant challenges in language modeling, resulting in divergent token sequences and output distributions. To overcome these limitations, we propose Vocabulary-agnostic Teacher Guided Language Modeling (VocAgnoLM), a novel approach that bridges the gap caused by vocabulary mismatch through two key methods: (1) Token-level Lexical Alignment, which aligns token sequences across mismatched vocabularies, and (2) Teacher Guided Loss, which leverages the loss of teacher model to guide effective student training. We demonstrate its effectiveness in language modeling with 1B student model using various 7B teacher models with different vocabularies. Notably, with Qwen2.5-Math-Instruct, a teacher model sharing only about 6% of its vocabulary with TinyLlama, VocAgnoLM achieves a 46% performance improvement compared to naive continual pretraining. Furthermore, we demonstrate that VocAgnoLM consistently benefits from stronger teacher models, providing a robust solution to vocabulary mismatches in language modeling.
format Preprint
id arxiv_https___arxiv_org_abs_2503_19123
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Overcoming Vocabulary Mismatch: Vocabulary-agnostic Teacher Guided Language Modeling
Shin, Haebin
Ji, Lei
Liu, Xiao
Gong, Yeyun
Computation and Language
Artificial Intelligence
Using large teacher models to guide the training of smaller student models has become the prevailing paradigm for efficient and effective learning. However, vocabulary mismatches between teacher and student language models pose significant challenges in language modeling, resulting in divergent token sequences and output distributions. To overcome these limitations, we propose Vocabulary-agnostic Teacher Guided Language Modeling (VocAgnoLM), a novel approach that bridges the gap caused by vocabulary mismatch through two key methods: (1) Token-level Lexical Alignment, which aligns token sequences across mismatched vocabularies, and (2) Teacher Guided Loss, which leverages the loss of teacher model to guide effective student training. We demonstrate its effectiveness in language modeling with 1B student model using various 7B teacher models with different vocabularies. Notably, with Qwen2.5-Math-Instruct, a teacher model sharing only about 6% of its vocabulary with TinyLlama, VocAgnoLM achieves a 46% performance improvement compared to naive continual pretraining. Furthermore, we demonstrate that VocAgnoLM consistently benefits from stronger teacher models, providing a robust solution to vocabulary mismatches in language modeling.
title Overcoming Vocabulary Mismatch: Vocabulary-agnostic Teacher Guided Language Modeling
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2503.19123