MUCH: A Multilingual Claim Hallucination Benchmark

Fuente: arXiv
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Autores principales: Dentan, Jérémie, Canesse, Alexi, Buscaldi, Davide, Shabou, Aymen, Vanier, Sonia
Formato: Preprint
Publicado: 2025
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author Dentan, Jérémie
Canesse, Alexi
Buscaldi, Davide
Shabou, Aymen
Vanier, Sonia
author_facet Dentan, Jérémie
Canesse, Alexi
Buscaldi, Davide
Shabou, Aymen
Vanier, Sonia
contents Claim-level Uncertainty Quantification (UQ) is a promising approach to mitigate the lack of reliability in Large Language Models (LLMs). We introduce MUCH, the first claim-level UQ benchmark designed for fair and reproducible evaluation of future methods under realistic conditions. It includes 4,873 samples across four European languages (English, French, Spanish, and German) and four instruction-tuned open-weight LLMs. Unlike prior claim-level benchmarks, we release 24 generation logits per token, facilitating the development of future white-box methods without re-generating data. Moreover, in contrast to previous benchmarks that rely on manual or LLM-based segmentation, we propose a new deterministic algorithm capable of segmenting claims using as little as 0.2% of the LLM generation time. This makes our segmentation approach suitable for real-time monitoring of LLM outputs, ensuring that MUCH evaluates UQ methods under realistic deployment constraints. Finally, our evaluations show that current methods still have substantial room for improvement in both performance and efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2511_17081
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MUCH: A Multilingual Claim Hallucination Benchmark
Dentan, Jérémie
Canesse, Alexi
Buscaldi, Davide
Shabou, Aymen
Vanier, Sonia
Computation and Language
Claim-level Uncertainty Quantification (UQ) is a promising approach to mitigate the lack of reliability in Large Language Models (LLMs). We introduce MUCH, the first claim-level UQ benchmark designed for fair and reproducible evaluation of future methods under realistic conditions. It includes 4,873 samples across four European languages (English, French, Spanish, and German) and four instruction-tuned open-weight LLMs. Unlike prior claim-level benchmarks, we release 24 generation logits per token, facilitating the development of future white-box methods without re-generating data. Moreover, in contrast to previous benchmarks that rely on manual or LLM-based segmentation, we propose a new deterministic algorithm capable of segmenting claims using as little as 0.2% of the LLM generation time. This makes our segmentation approach suitable for real-time monitoring of LLM outputs, ensuring that MUCH evaluates UQ methods under realistic deployment constraints. Finally, our evaluations show that current methods still have substantial room for improvement in both performance and efficiency.
title MUCH: A Multilingual Claim Hallucination Benchmark
topic Computation and Language
url https://arxiv.org/abs/2511.17081