RichRAG: Crafting Rich Responses for Multi-faceted Queries in Retrieval-Augmented Generation

TL;DR

RichRAG is a novel retrieval-augmented generation framework designed to produce rich, multi-faceted responses to broad, open-ended queries by identifying sub-aspects, retrieving diverse documents, and ranking them to guide comprehensive answer generation.

Contribution

The paper introduces RichRAG, a new framework with sub-aspect exploration, multi-faceted retrieval, and list-wise ranking to enhance response richness in retrieval-augmented generation.

Findings

Effective in generating comprehensive responses

Outperforms baselines on public datasets

Improves coverage of query aspects

Abstract

Retrieval-augmented generation (RAG) effectively addresses issues of static knowledge and hallucination in large language models. Existing studies mostly focus on question scenarios with clear user intents and concise answers. However, it is prevalent that users issue broad, open-ended queries with diverse sub-intents, for which they desire rich and long-form answers covering multiple relevant aspects. To tackle this important yet underexplored problem, we propose a novel RAG framework, namely RichRAG. It includes a sub-aspect explorer to identify potential sub-aspects of input questions, a multi-faceted retriever to build a candidate pool of diverse external documents related to these sub-aspects, and a generative list-wise ranker, which is a key module to provide the top-k most valuable documents for the final generator. These ranked documents sufficiently cover various query aspects and are aware of the generator's preferences, hence incentivizing it to produce rich and comprehensive responses for users. The training of our ranker involves a supervised fine-tuning stage to ensure the basic coverage of documents, and a reinforcement learning stage to align downstream LLM's preferences to the ranking of documents. Experimental results on two publicly available datasets prove that our framework effectively and efficiently provides comprehensive and satisfying responses to users.