Dense X Retrieval: What Retrieval Granularity Should We Use?
Authors: Tong Chen, Hongwei Wang, Sihao Chen, Wenhao Yu, Kaixin Ma, Xinran Zhao, Hongming Zhang, Dong Yu
AI-generated Key Points
- Proposition retrieval outperforms passage or sentence-based methods in both passage retrieval accuracy and downstream QA performance
- FACTOIDWIKI is an indexed version of the English Wikipedia dump, segmented into 250 million propositions
- Proposition retrieval demonstrates higher success rates compared to sentence and passage retrieval methods within the range of 100-200 words
- Passage-level retrieval struggles with entity ambiguity and references, while sentence-based retrieval lacks context
- Proposition-based retrieval ensures each unit contains one factoid and necessary context
- Proposition-based retrieval faces challenges with questions involving multi-hop reasoning over long-range textual analysis
- Recent works on dense retrievers typically adopt a dual-encoder architecture to improve retrieval performance
- This study provides insights into the impact of different types of retrievals on dense retrievals and downstream QA tasks
Abstract: Dense retrieval has become a prominent method to obtain relevant context or world knowledge in open-domain NLP tasks. When we use a learned dense retriever on a retrieval corpus at inference time, an often-overlooked design choice is the retrieval unit in which the corpus is indexed, e.g. document, passage, or sentence. We discover that the retrieval unit choice significantly impacts the performance of both retrieval and downstream tasks. Distinct from the typical approach of using passages or sentences, we introduce a novel retrieval unit, proposition, for dense retrieval. Propositions are defined as atomic expressions within text, each encapsulating a distinct factoid and presented in a concise, self-contained natural language format. We conduct an empirical comparison of different retrieval granularity. Our results reveal that proposition-based retrieval significantly outperforms traditional passage or sentence-based methods in dense retrieval. Moreover, retrieval by proposition also enhances the performance of downstream QA tasks, since the retrieved texts are more condensed with question-relevant information, reducing the need for lengthy input tokens and minimizing the inclusion of extraneous, irrelevant information.
Tools for this paper
Ask questions about this paper to our AI assistant
You can also chat with multiple papers at once here.
The previous summary was created more than a year ago and can be re-run (if necessary) by clicking on the Run button below.
Similar papers summarized with our AI tools
Navigate through even more similar papers through a
tree representationLook for similar papers (in beta version)
We compare the title and abstract with papers indexed in our database. For arXiv papers, we search within the same category; for DOI and other sources, we search across sources and subjects. You can rerun the search as our database grows.
Disclaimer: The AI-based summarization tool and virtual assistant provided on this website may not always provide accurate and complete summaries or responses. We encourage you to carefully review and evaluate the generated content to ensure its quality and relevance to your needs.