R1-Ranker: Teaching LLM Rankers to Reason

Fuente: arXiv
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Auteurs principaux: Feng, Tao, Hua, Zhigang, Lei, Zijie, Xie, Yan, Yang, Shuang, Long, Bo, You, Jiaxuan
Format: Preprint
Publié: 2025
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author Feng, Tao
Hua, Zhigang
Lei, Zijie
Xie, Yan
Yang, Shuang
Long, Bo
You, Jiaxuan
author_facet Feng, Tao
Hua, Zhigang
Lei, Zijie
Xie, Yan
Yang, Shuang
Long, Bo
You, Jiaxuan
contents Large language models (LLMs) have recently shown strong reasoning abilities in domains like mathematics, coding, and scientific problem-solving, yet their potential for ranking tasks, where prime examples include retrieval, recommender systems, and LLM routing, remains underexplored. Ranking requires complex reasoning across heterogeneous candidates, but existing LLM-based rankers are often domain-specific, tied to fixed backbones, and lack iterative refinement, limiting their ability to fully exploit LLMs' reasoning potential. To address these challenges, we propose R1-Ranker, a reasoning-incentive framework built on reinforcement learning, with two complementary designs: DRanker, which generates full rankings in one shot, and IRanker, which decomposes ranking into an iterative elimination process with step-wise rewards to encourage deeper reasoning. We evaluate unified R1-Rankers on nine datasets spanning recommendation, routing, and passage ranking, showing that IRanker-3B consistently achieves state-of-the-art performance, surpasses larger 7B models on some tasks, and yields a 15.7% average relative improvement. Ablation and generalization experiments further confirm the critical role of reinforcement learning and iterative reasoning, with IRanker-3B improving zero-shot performance by over 9% on out-of-domain tasks and reasoning traces boosting other LLMs by up to 22.87%. These results demonstrate that unifying diverse ranking tasks with a single reasoning-driven foundation model is both effective and essential for advancing LLM reasoning in ranking scenarios.
format Preprint
id arxiv_https___arxiv_org_abs_2506_21638
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle R1-Ranker: Teaching LLM Rankers to Reason
Feng, Tao
Hua, Zhigang
Lei, Zijie
Xie, Yan
Yang, Shuang
Long, Bo
You, Jiaxuan
Information Retrieval
Artificial Intelligence
Machine Learning
Large language models (LLMs) have recently shown strong reasoning abilities in domains like mathematics, coding, and scientific problem-solving, yet their potential for ranking tasks, where prime examples include retrieval, recommender systems, and LLM routing, remains underexplored. Ranking requires complex reasoning across heterogeneous candidates, but existing LLM-based rankers are often domain-specific, tied to fixed backbones, and lack iterative refinement, limiting their ability to fully exploit LLMs' reasoning potential. To address these challenges, we propose R1-Ranker, a reasoning-incentive framework built on reinforcement learning, with two complementary designs: DRanker, which generates full rankings in one shot, and IRanker, which decomposes ranking into an iterative elimination process with step-wise rewards to encourage deeper reasoning. We evaluate unified R1-Rankers on nine datasets spanning recommendation, routing, and passage ranking, showing that IRanker-3B consistently achieves state-of-the-art performance, surpasses larger 7B models on some tasks, and yields a 15.7% average relative improvement. Ablation and generalization experiments further confirm the critical role of reinforcement learning and iterative reasoning, with IRanker-3B improving zero-shot performance by over 9% on out-of-domain tasks and reasoning traces boosting other LLMs by up to 22.87%. These results demonstrate that unifying diverse ranking tasks with a single reasoning-driven foundation model is both effective and essential for advancing LLM reasoning in ranking scenarios.
title R1-Ranker: Teaching LLM Rankers to Reason
topic Information Retrieval
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2506.21638