Expand, Highlight, Generate: RL-driven Document Generation for Passage Reranking

Arian Askari, Mohammad Aliannejadi, Chuan Meng, Evangelos Kanoulas, Suzan Verberne

Submission Type: Regular Long Paper

Submission Track: Information Retrieval and Text Mining

Keywords: Synthetic document generation, Data augmentation, Information retrieval

TL;DR: This paper presents novel synthetic document generators for data augmentation in information retrieval, leveraging generative large language models to produce synthetic documents and enhance query quality, leading to effective retrieval models.

Abstract: Generating synthetic training data based on large language models (LLMs) for ranking models has gained attention recently. Prior studies use LLMs to build pseudo query-document pairs by generating synthetic queries from documents in a corpus. In this paper, we propose a new perspective of data augmentation: generating synthetic documents from queries. To achieve this, we propose DocGen, that consists of a three-step pipeline that utilizes the few-shot capabilities of LLMs. DocGen pipeline performs synthetic document generation by (i) expanding, (ii) highlighting the original query, and then (iii) generating a synthetic document that is likely to be relevant to the query. To further improve the relevance between generated synthetic documents and their corresponding queries, we propose DocGen-RL, which regards the estimated relevance of the document as a reward and leverages reinforcement learning (RL) to optimize DocGen pipeline. Extensive experiments demonstrate that DocGen pipeline and DocGen-RL significantly outperform existing state-of-theart data augmentation methods, such as InPars, indicating that our new perspective of generating documents leverages the capacity of LLMs in generating synthetic data more effectively. We release the code, generated data, and model checkpoints to foster research in this area.

Submission Number: 2105