ProRank: Prompt Warmup via Reinforcement Learning for Small Language Models Reranking

Fuente: arXiv
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Hauptverfasser: Li, Xianming, Shakir, Aamir, Huang, Rui, Lee, Tsz-fung Andrew, Lipp, Julius, Clavié, Benjamin, Li, Jing
Format: Preprint
Veröffentlicht: 2025
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author Li, Xianming
Shakir, Aamir
Huang, Rui
Lee, Tsz-fung Andrew
Lipp, Julius
Clavié, Benjamin
Li, Jing
author_facet Li, Xianming
Shakir, Aamir
Huang, Rui
Lee, Tsz-fung Andrew
Lipp, Julius
Clavié, Benjamin
Li, Jing
contents Reranking is fundamental to information retrieval and retrieval-augmented generation, with recent Large Language Models (LLMs) significantly advancing reranking quality. Most current works rely on large-scale LLMs (>7B parameters), presenting high computational costs. Small Language Models (SLMs) offer a promising alternative because of computational efficiency. However, our preliminary quantitative analysis reveals key limitations of SLMs: their representation space is narrow, leading to reduced expressiveness, and they struggle with understanding task prompts without fine-tuning. To address these issues, we introduce a novel two-stage training approach, ProRank, for SLM-based document reranking. We propose using reinforcement learning to improve the understanding of task prompts. Additionally, we introduce fine-grained score learning to enhance representation expressiveness and further improve document reranking quality. Extensive experiments suggest that ProRank consistently outperforms both the most advanced open-source and proprietary reranking models. Notably, our 0.5B ProRank even surpasses powerful LLM reranking models on the BEIR benchmark, establishing that properly trained SLMs can achieve superior document reranking performance while maintaining computational efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2506_03487
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle ProRank: Prompt Warmup via Reinforcement Learning for Small Language Models Reranking
Li, Xianming
Shakir, Aamir
Huang, Rui
Lee, Tsz-fung Andrew
Lipp, Julius
Clavié, Benjamin
Li, Jing
Information Retrieval
Computation and Language
Reranking is fundamental to information retrieval and retrieval-augmented generation, with recent Large Language Models (LLMs) significantly advancing reranking quality. Most current works rely on large-scale LLMs (>7B parameters), presenting high computational costs. Small Language Models (SLMs) offer a promising alternative because of computational efficiency. However, our preliminary quantitative analysis reveals key limitations of SLMs: their representation space is narrow, leading to reduced expressiveness, and they struggle with understanding task prompts without fine-tuning. To address these issues, we introduce a novel two-stage training approach, ProRank, for SLM-based document reranking. We propose using reinforcement learning to improve the understanding of task prompts. Additionally, we introduce fine-grained score learning to enhance representation expressiveness and further improve document reranking quality. Extensive experiments suggest that ProRank consistently outperforms both the most advanced open-source and proprietary reranking models. Notably, our 0.5B ProRank even surpasses powerful LLM reranking models on the BEIR benchmark, establishing that properly trained SLMs can achieve superior document reranking performance while maintaining computational efficiency.
title ProRank: Prompt Warmup via Reinforcement Learning for Small Language Models Reranking
topic Information Retrieval
Computation and Language
url https://arxiv.org/abs/2506.03487