Overview of the CLEF-2025 CheckThat! Lab Task 2 on Claim Normalization
Sundriyal, Megha Chakraborty, Tanmoy Nakov, Preslav Ivanov
Sundriyal, Megha
Chakraborty, Tanmoy
Nakov, Preslav Ivanov
Supervisor
Department
Natural Language Processing
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Type
Conference proceeding
Date
2025
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Language
English
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Abstract
We present an overview of Task 2 from CheckThat! at CLEF 2025, which focuses on claim normalization. The tasks asks systems to transform informal and often noisy social media posts into clear, concise, and verifiable statements known as normalized claims, which capture the core factual assertion of a post, which makes them much easier to verify and fact-check. The task is especially relevant in multilingual and low-resource contexts, where the diversity of languages and limited labelled data pose serious challenges. Task 2 was conducted in two distinct settings: (i) monolingual, where systems were trained and tested on the same language, and (ii) zero-shot, where models had to normalize claims in a new target language without any in-language training data. The monolingual track covered thirteen languages, including English, German, French, Spanish, Portugese, Hindi, Marathi, Punjabi, Tamil, Arabic, Thai, Indonesian, and Polish. While the zero-shot setting introduced seven more languages, such as Dutch, Romanian, Bengali, Telugu, Korean, Greek, and Czech. This structure allowed us to evaluate both language-specific performance and cross-lingual generalization. In total, 18 teams participated in Task 2, submitting 1,226 valid runs across the two settings. The submissions were evaluated using the METEOR score. Many teams leveraged transformer-based models, multilingual embeddings, and retrieval-augmented strategies. In this paper, we outline the task setup, give details about the datasets, and provide a detailed summary of the diverse approaches adopted by the participating teams.
Citation
M. Sundriyal, T. Chakraborty, and P. Nakov, “Overview of the CLEF-2025 CheckThat! Lab Task 2 on Claim Normalization,” CEUR Workshop Proc, 2025
Source
CEUR Workshop Proceedings
Conference
26th Working Notes of the Conference and Labs of the Evaluation Forum, CLEF 2025
Keywords
Claim Normalization, Claims, Multilinguality, Social Media Posts
Subjects
Source
26th Working Notes of the Conference and Labs of the Evaluation Forum, CLEF 2025
Publisher
CEUR-WS