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LREC 2026main

Very Large-Scale Multilingual Resources for LLMs and MT. Mono- and Bi-lingual Data, Multilingual Evaluation, and Pre-Trained Models

Proceedings of the Fifteenth Language Resources and Evaluation Conference (LREC 2026)

DOI:10.63317/25xbdofco9od

Abstract

We present an ongoing initiative to provide open, very large, high-quality, and richly annotated textual datasets for almost 200 languages. At 30 trillion tokens, this is likely the largest generally available multilingual collection of LLM pre-training data. These datasets are derived from web crawls from different sources and accompanied with a complete, open-source pipeline for document selection from web archives, text extraction from HTML, language identification for noisy texts, exact and near-deduplication, annotation with, among others, register labels, text quality estimates, and personally identifiable information; and final selection and filtering. We report on data quality probes through contrastive and analytical statistics, through manual inspection of samples for some 20 languages, and through end-to-end evaluation of various language model architectures trained on this data. For multilingual LLM evaluation, we provide a comprehensive collection of benchmarks for nine European languages, with special emphasis on natively created tasks, mechanisms to mitigate prompt sensitivity, and refined normalization and aggregation of scores. Additionally, we train and evaluate a family of 57 monolingual encoder–decoder models, as well as about 30 “smallish” monolingual GPT-like reference models. Besides the monolingual data and models, we also present a very large collection of parallel texts automatically mined from this data, together with a novel parallel corpus synthesized via machine translation.

Details

Paper ID
lrec2026-main-110
Pages
pp. 1409-1434
BibKey
oepen-etal-2026-very
Editor
N/A
Publisher
European Language Resources Association (ELRA)
ISSN
2522-2686
ISBN
978-2-493814-49-4
Conference
The Fifteenth Language Resources and Evaluation Conference (LREC 2026)
Location
Palma, Mallorca, Spain
Date
11 May 2026 16 May 2026

Authors

  • SO

    Stephan Oepen

  • NA

    Nikolay Arefyev

  • MA

    Mikko Aulamo

  • MB

    Marta Bañón

  • MB

    Maja Buljan

  • LB

    Laurie V. Burchell

  • LC

    Lucas Georges Gabriel Charpentier

  • PC

    Pinzhen Chen

  • MF

    Mariia Fedorova

  • OG

    Ona de Gibert

  • BH

    Barry Haddow

  • JH

    Jan Hajič

  • JH

    Jindrich Helcl

  • AK

    Andrey Kutuzov

  • VL

    Veronika Laippala

  • ZL

    Zihao Li

  • BM

    Bhavitvya Malik

  • VM

    Vladislav Mikhailov

  • AM

    Amanda Myntti

  • DO

    Dayyán O'Brien

  • LP

    Lucie Polakova

  • GR

    Gema Ramírez-Sánchez

  • JS

    Janine Siewert

  • PS

    Pavel Stepachev

  • JT

    Joerg Tiedemann

  • TV

    Teemu Vahtola

  • DV

    Dusan Varis

  • FV

    Fedor Vitiugin

  • JZ

    Jaume Zaragoza

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