CONF Kew_EMNLP2023_2023/IDIAP BLESS: Benchmarking Large Language Models on Sentence Simplification Kew, Tannon Chi, Alison Vásquez-Rodríguez, Laura Agrawal, Sweta Aumiller, Dennis Alva-Manchego, Fernando Shardlow, Matthew evaluation LLM NLP Text Simplification EXTERNAL http://publications.idiap.ch/attachments/papers/2023/Kew_EMNLP2023_2023.pdf PUBLIC Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing Singapore 2023 We present BLESS, a comprehensive performance benchmark of the most recent state-of-the-art large language models (LLMs) on the task of text simplification (TS). We examine how well off-the-shelf LLMs can solve this challenging task, assessing a total of 44 models, differing in size, architecture, pre-training methods, and accessibility, on three test sets from different domains (Wikipedia, news, and medical) under a few-shot setting. Our analysis considers a suite of automatic metrics as well as a large-scale quantitative investigation into the types of common edit operations performed by the different models. Furthermore, we perform a manual qualitative analysis on a subset of model outputs to better gauge the quality of the generated simplifications. Our evaluation indicates that the best LLMs, despite not being trained on TS, perform comparably with state-of-the-art TS baselines. Additionally, we find that certain LLMs demonstrate a greater range and diversity of edit operations. Our performance benchmark will be available as a resource for the development of future TS methods and evaluation metrics.