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Main Authors: Jiang, Yi, Zhao, Sendong, Li, Jianbo, Hu, Bairui, Du, Yanrui, Wang, Haochun, Qin, Bing
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2601.05027
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author Jiang, Yi
Zhao, Sendong
Li, Jianbo
Hu, Bairui
Du, Yanrui
Wang, Haochun
Qin, Bing
author_facet Jiang, Yi
Zhao, Sendong
Li, Jianbo
Hu, Bairui
Du, Yanrui
Wang, Haochun
Qin, Bing
contents Retrieval-Augmented Generation (RAG) improves generation quality by incorporating evidence retrieved from large external corpora. However, most existing methods rely on statically selecting top-k passages based on individual relevance, which fails to exploit combinatorial gains among passages and often introduces substantial redundancy. To address this limitation, we propose OptiSet, a set-centric framework that unifies set selection and set-level ranking for RAG. OptiSet adopts an "Expand-then-Refine" paradigm: it first expands a query into multiple perspectives to enable a diverse candidate pool and then refines the candidate pool via re-selection to form a compact evidence set. We then devise a self-synthesis strategy without strong LLM supervision to derive preference labels from the set conditional utility changes of the generator, thereby identifying complementary and redundant evidence. Finally, we introduce a set-list wise training strategy that jointly optimizes set selection and set-level ranking, enabling the model to favor compact, high-gain evidence sets. Extensive experiments demonstrate that OptiSet improves performance on complex combinatorial problems and makes generation more efficient. The source code is publicly available.
format Preprint
id arxiv_https___arxiv_org_abs_2601_05027
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle OptiSet: Unified Optimizing Set Selection and Ranking for Retrieval-Augmented Generation
Jiang, Yi
Zhao, Sendong
Li, Jianbo
Hu, Bairui
Du, Yanrui
Wang, Haochun
Qin, Bing
Artificial Intelligence
Retrieval-Augmented Generation (RAG) improves generation quality by incorporating evidence retrieved from large external corpora. However, most existing methods rely on statically selecting top-k passages based on individual relevance, which fails to exploit combinatorial gains among passages and often introduces substantial redundancy. To address this limitation, we propose OptiSet, a set-centric framework that unifies set selection and set-level ranking for RAG. OptiSet adopts an "Expand-then-Refine" paradigm: it first expands a query into multiple perspectives to enable a diverse candidate pool and then refines the candidate pool via re-selection to form a compact evidence set. We then devise a self-synthesis strategy without strong LLM supervision to derive preference labels from the set conditional utility changes of the generator, thereby identifying complementary and redundant evidence. Finally, we introduce a set-list wise training strategy that jointly optimizes set selection and set-level ranking, enabling the model to favor compact, high-gain evidence sets. Extensive experiments demonstrate that OptiSet improves performance on complex combinatorial problems and makes generation more efficient. The source code is publicly available.
title OptiSet: Unified Optimizing Set Selection and Ranking for Retrieval-Augmented Generation
topic Artificial Intelligence
url https://arxiv.org/abs/2601.05027