EstLLM: Enhancing Estonian Capabilities in Multilingual LLMs via Continued Pretraining and Post-Training

Fuente: arXiv
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Autori principali: Dorkin, Aleksei, Purason, Taido, Kalbaliyev, Emil, Kuulmets, Hele-Andra, Ojastu, Marii, Fišel, Mark, Alumäe, Tanel, Aedmaa, Eleri, Kruusmaa, Krister, Sirts, Kairit
Natura: Preprint
Pubblicazione: 2026
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author Dorkin, Aleksei
Purason, Taido
Kalbaliyev, Emil
Kuulmets, Hele-Andra
Ojastu, Marii
Fišel, Mark
Alumäe, Tanel
Aedmaa, Eleri
Kruusmaa, Krister
Sirts, Kairit
author_facet Dorkin, Aleksei
Purason, Taido
Kalbaliyev, Emil
Kuulmets, Hele-Andra
Ojastu, Marii
Fišel, Mark
Alumäe, Tanel
Aedmaa, Eleri
Kruusmaa, Krister
Sirts, Kairit
contents Large language models (LLMs) are predominantly trained on English-centric data, resulting in uneven performance for smaller languages. We study whether continued pretraining (CPT) can substantially improve Estonian capabilities in a pretrained multilingual LLM while preserving its English and general reasoning performance. Using Llama 3.1 8B as the main base model, we perform CPT on a mixture that increases Estonian exposure while approximating the original training distribution through English replay and the inclusion of code, mathematics, and instruction-like data. We subsequently apply supervised fine-tuning, preference optimization, and chat vector merging to introduce robust instruction-following behavior. Evaluation on a comprehensive suite of Estonian benchmarks shows consistent gains in linguistic competence, knowledge, reasoning, translation quality, and instruction-following compared to the original base model and its instruction-tuned variant, while maintaining competitive performance on English benchmarks. These findings indicate that CPT, with an appropriately balanced data mixture, together with post-training alignment, can substantially improve single-language capabilities in pretrained multilingual LLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2603_02041
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle EstLLM: Enhancing Estonian Capabilities in Multilingual LLMs via Continued Pretraining and Post-Training
Dorkin, Aleksei
Purason, Taido
Kalbaliyev, Emil
Kuulmets, Hele-Andra
Ojastu, Marii
Fišel, Mark
Alumäe, Tanel
Aedmaa, Eleri
Kruusmaa, Krister
Sirts, Kairit
Computation and Language
Artificial Intelligence
Large language models (LLMs) are predominantly trained on English-centric data, resulting in uneven performance for smaller languages. We study whether continued pretraining (CPT) can substantially improve Estonian capabilities in a pretrained multilingual LLM while preserving its English and general reasoning performance. Using Llama 3.1 8B as the main base model, we perform CPT on a mixture that increases Estonian exposure while approximating the original training distribution through English replay and the inclusion of code, mathematics, and instruction-like data. We subsequently apply supervised fine-tuning, preference optimization, and chat vector merging to introduce robust instruction-following behavior. Evaluation on a comprehensive suite of Estonian benchmarks shows consistent gains in linguistic competence, knowledge, reasoning, translation quality, and instruction-following compared to the original base model and its instruction-tuned variant, while maintaining competitive performance on English benchmarks. These findings indicate that CPT, with an appropriately balanced data mixture, together with post-training alignment, can substantially improve single-language capabilities in pretrained multilingual LLMs.
title EstLLM: Enhancing Estonian Capabilities in Multilingual LLMs via Continued Pretraining and Post-Training
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2603.02041