Optimized for AI: Curating the Icelandic Gigaword Corpus for Stable LLM Training

Jón Friðrik Daðason, Steinþór Steingrímsson


Abstract
The Icelandic Gigaword Corpus (IGC) is a primary resource for Icelandic NLP, with its current version containing 2.7 billion words of curated text. The IGC is traditionally distributed in a TEI-XML format, a hierarchical structure that allows for rich linguistic annotation and metadata. However, this format introduces significant friction for modern machine learning workflows. Even high-quality curated corpora have been found to contain “unwanted” text sequences – such as fragmented lists or repetitive boilerplate that may trigger instabilities during training of large language models. In this paper, we present a new processing pipeline designed to optimize the IGC for AI development. We describe a filtering approach focusing on training stability, including fuzzy deduplication to reduce the risk of data leakage, with the aim to provide high-quality data for stable model convergence. Furthermore, we introduce a new JSONL distribution format that bridges the gap between TEI-XML and machine-actionable data, facilitating easier access and safer training for models aiming to work with Icelandic.
Anthology ID:
2026.cmlc-1.6
Volume:
Proceedings of the 12th Workshop on Challenges in the Management of Large Corpora
Month:
May
Year:
2026
Address:
Palma, Mallorca (Spain)
Editors:
Piotr Bański, Dawn Knight, Marc Kupietz, Andreas Witt, Alina Wróblewska
Venues:
CMLC | WS
SIG:
Publisher:
ELRA Language Resources Association (ELRA)
Note:
Pages:
49–56
Language:
External URL:
https://lrec.elra.info/lrec2026-ws-cmlc-06
DOI:
10.63317/3uatbht8mdrf
Bibkey:
Cite (ACL):
Jón Friðrik Daðason and Steinþór Steingrímsson. 2026. Optimized for AI: Curating the Icelandic Gigaword Corpus for Stable LLM Training. In Proceedings of the 12th Workshop on Challenges in the Management of Large Corpora, pages 49–56, Palma, Mallorca (Spain). ELRA Language Resources Association (ELRA).
Cite (Informal):
Optimized for AI: Curating the Icelandic Gigaword Corpus for Stable LLM Training (Daðason & Steingrímsson, CMLC 2026)
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