Summary of a Haystack: A Challenge to Long-Context LLMs and RAG Systems

Philippe Laban, Alexander Fabbri, Caiming Xiong, Chien-Sheng Wu


Abstract
LLMs and RAG systems are now capable of handling millions of input tokens or more. However, evaluating the output quality of such systems on long-context tasks remains challenging, as tasks like Needle-in-a-Haystack lack complexity. In this work, we argue that summarization can play a central role in such evaluation. We design a procedure to synthesize Haystacks of documents, ensuring that specific insights repeat across documents. The “Summary of a Haystack” (SummHay) task then requires a system to process the Haystack and generate, given a query, a summary that identifies the relevant insights and precisely cites the source documents. Since we have precise knowledge of what insights should appear in a haystack summary and what documents should be cited, we implement a highly reproducible automatic evaluation that can score summaries on two aspects – Coverage and Citation. We generate Haystacks in two domains (conversation, news), and perform a large-scale evaluation of 10 LLMs and corresponding 50 RAG systems. Our findings indicate that SummHay is an open challenge for current systems, as even systems provided with an Oracle signal of document relevance lag our estimate of human performance (56%) by 10+ points on a Joint Score. Without a retriever, long-context LLMs like GPT-4o and Claude 3 Opus score below 20% on SummHay. We show SummHay can also be used to study enterprise RAG systems and position bias in long-context models. We hope future systems can equal and surpass human performance on SummHay.
Anthology ID:
2024.emnlp-main.552
Volume:
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing
Month:
November
Year:
2024
Address:
Miami, Florida, USA
Editors:
Yaser Al-Onaizan, Mohit Bansal, Yun-Nung Chen
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
9885–9903
Language:
URL:
https://aclanthology.org/2024.emnlp-main.552
DOI:
10.18653/v1/2024.emnlp-main.552
Bibkey:
Cite (ACL):
Philippe Laban, Alexander Fabbri, Caiming Xiong, and Chien-Sheng Wu. 2024. Summary of a Haystack: A Challenge to Long-Context LLMs and RAG Systems. In Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing, pages 9885–9903, Miami, Florida, USA. Association for Computational Linguistics.
Cite (Informal):
Summary of a Haystack: A Challenge to Long-Context LLMs and RAG Systems (Laban et al., EMNLP 2024)
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PDF:
https://aclanthology.org/2024.emnlp-main.552.pdf