@inproceedings{chakar-etal-2026-benchmark,
title = "A Benchmark for Overgeneration Detection in Biomedical Text Simplification",
author = "Chakar, Berkay and
Ermakova, Liana and
Kamps, Jaap",
editor = "Di Nunzio, Giorgio Maria and
Vezzani, Federica and
Ermakova, Liana and
Azarbonyad, Hosein and
Kamps, Jaap",
booktitle = "Proceedings of the 2nd Workshop on Evaluating Text Difficulty in a Multilingual Context ({D}e{T}erm{I}t! 2026)",
month = may,
year = "2026",
address = "Palma, Mallorca (Spain)",
publisher = "ELRA Language Resources Association (ELRA)",
url = "https://aclanthology.org/2026.determit-1.2/",
doi = "10.63317/3aodve3ow6a7",
pages = "12--21",
abstract = "Large Language Models deployed for biomedical text simplification frequently produce overgeneration: extraneous content appended beyond the faithful simplification, including leaked model instructions, ungrounded medical claims, and repetitive text. Despite its prevalence, this failure mode remains largely unaddressed. We present a benchmark for document-level overgeneration detection, releasing two resources: SimpleOG-manual, 500 abstract-level examples with human-validated positive labels, and SimpleOG-auto, over 46,000 automatically labeled abstract-level examples derived from submissions to the CLEF 2025 SimpleText Track. Our method exploits the positional regularity of overgeneration in simplification output through sequence alignment, identifying trailing content that lacks a corresponding segment in the source. Human validation of 117 automatically flagged positives confirms {\ensuremath{\sim}}95{\%} precision, with leaked model instructions accounting for 75.7{\%} of confirmed cases. Analysis across teams and models reveals that overgeneration is primarily driven by system-level choices, such as prompting and post-processing, rather than by model architecture. We evaluate three detection paradigms and find that sentence similarity (F1 = 0.731, ROC-AUC = 0.915) surprisingly outperforms both NLI-based and LLM-based approaches, suggesting that overgenerated content occupies distinct semantic regions from source material."
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<abstract>Large Language Models deployed for biomedical text simplification frequently produce overgeneration: extraneous content appended beyond the faithful simplification, including leaked model instructions, ungrounded medical claims, and repetitive text. Despite its prevalence, this failure mode remains largely unaddressed. We present a benchmark for document-level overgeneration detection, releasing two resources: SimpleOG-manual, 500 abstract-level examples with human-validated positive labels, and SimpleOG-auto, over 46,000 automatically labeled abstract-level examples derived from submissions to the CLEF 2025 SimpleText Track. Our method exploits the positional regularity of overgeneration in simplification output through sequence alignment, identifying trailing content that lacks a corresponding segment in the source. Human validation of 117 automatically flagged positives confirms \ensuremath\sim95% precision, with leaked model instructions accounting for 75.7% of confirmed cases. Analysis across teams and models reveals that overgeneration is primarily driven by system-level choices, such as prompting and post-processing, rather than by model architecture. We evaluate three detection paradigms and find that sentence similarity (F1 = 0.731, ROC-AUC = 0.915) surprisingly outperforms both NLI-based and LLM-based approaches, suggesting that overgenerated content occupies distinct semantic regions from source material.</abstract>
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%0 Conference Proceedings
%T A Benchmark for Overgeneration Detection in Biomedical Text Simplification
%A Chakar, Berkay
%A Ermakova, Liana
%A Kamps, Jaap
%Y Di Nunzio, Giorgio Maria
%Y Vezzani, Federica
%Y Ermakova, Liana
%Y Azarbonyad, Hosein
%Y Kamps, Jaap
%S Proceedings of the 2nd Workshop on Evaluating Text Difficulty in a Multilingual Context (DeTermIt! 2026)
%D 2026
%8 May
%I ELRA Language Resources Association (ELRA)
%C Palma, Mallorca (Spain)
%F chakar-etal-2026-benchmark
%X Large Language Models deployed for biomedical text simplification frequently produce overgeneration: extraneous content appended beyond the faithful simplification, including leaked model instructions, ungrounded medical claims, and repetitive text. Despite its prevalence, this failure mode remains largely unaddressed. We present a benchmark for document-level overgeneration detection, releasing two resources: SimpleOG-manual, 500 abstract-level examples with human-validated positive labels, and SimpleOG-auto, over 46,000 automatically labeled abstract-level examples derived from submissions to the CLEF 2025 SimpleText Track. Our method exploits the positional regularity of overgeneration in simplification output through sequence alignment, identifying trailing content that lacks a corresponding segment in the source. Human validation of 117 automatically flagged positives confirms \ensuremath\sim95% precision, with leaked model instructions accounting for 75.7% of confirmed cases. Analysis across teams and models reveals that overgeneration is primarily driven by system-level choices, such as prompting and post-processing, rather than by model architecture. We evaluate three detection paradigms and find that sentence similarity (F1 = 0.731, ROC-AUC = 0.915) surprisingly outperforms both NLI-based and LLM-based approaches, suggesting that overgenerated content occupies distinct semantic regions from source material.
%R 10.63317/3aodve3ow6a7
%U https://aclanthology.org/2026.determit-1.2/
%U https://doi.org/10.63317/3aodve3ow6a7
%P 12-21
Markdown (Informal)
[A Benchmark for Overgeneration Detection in Biomedical Text Simplification](https://aclanthology.org/2026.determit-1.2/) (Chakar et al., DeTermIt 2026)
ACL