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Main Authors: Li, Tianjian, Zhang, Yiming, Yu, Ping, Saha, Swarnadeep, Khashabi, Daniel, Weston, Jason, Lanchantin, Jack, Wang, Tianlu
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.02534
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author Li, Tianjian
Zhang, Yiming
Yu, Ping
Saha, Swarnadeep
Khashabi, Daniel
Weston, Jason
Lanchantin, Jack
Wang, Tianlu
author_facet Li, Tianjian
Zhang, Yiming
Yu, Ping
Saha, Swarnadeep
Khashabi, Daniel
Weston, Jason
Lanchantin, Jack
Wang, Tianlu
contents Post-training of Large Language Models (LMs) often prioritizes accuracy and helpfulness at the expense of diversity. This creates a tension: while post-training improves response quality, it also sharpens output distributions and reduces the range of ideas, limiting the usefulness of LMs in creative and exploratory tasks such as brainstorming, storytelling, or problem solving. We address this challenge with Diversity-Aware Reinforcement Learning (DARLING), a framework that jointly optimizes for response quality and semantic diversity. At its core, DARLING introduces a learned partition function to measure diversity beyond surface-level lexical variations. This diversity signal is then combined with a quality reward during online reinforcement learning, encouraging models to generate outputs that are both high-quality and distinct. Experiments across multiple model families and sizes show that DARLING generalizes to two regimes: non-verifiable tasks (instruction following and creative writing) and verifiable tasks (competition math). On five benchmarks in the first setting, DARLING consistently outperforms quality-only RL baselines, producing outputs that are simultaneously of higher quality and novelty. In the second setting, DARLING achieves higher pass@1 (solution quality) and pass@k (solution variety). Most strikingly, explicitly optimizing for diversity catalyzes exploration in online RL, which manifests itself as higher-quality responses.
format Preprint
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publishDate 2025
record_format arxiv
spellingShingle Jointly Reinforcing Diversity and Quality in Language Model Generations
Li, Tianjian
Zhang, Yiming
Yu, Ping
Saha, Swarnadeep
Khashabi, Daniel
Weston, Jason
Lanchantin, Jack
Wang, Tianlu
Computation and Language
Machine Learning
Post-training of Large Language Models (LMs) often prioritizes accuracy and helpfulness at the expense of diversity. This creates a tension: while post-training improves response quality, it also sharpens output distributions and reduces the range of ideas, limiting the usefulness of LMs in creative and exploratory tasks such as brainstorming, storytelling, or problem solving. We address this challenge with Diversity-Aware Reinforcement Learning (DARLING), a framework that jointly optimizes for response quality and semantic diversity. At its core, DARLING introduces a learned partition function to measure diversity beyond surface-level lexical variations. This diversity signal is then combined with a quality reward during online reinforcement learning, encouraging models to generate outputs that are both high-quality and distinct. Experiments across multiple model families and sizes show that DARLING generalizes to two regimes: non-verifiable tasks (instruction following and creative writing) and verifiable tasks (competition math). On five benchmarks in the first setting, DARLING consistently outperforms quality-only RL baselines, producing outputs that are simultaneously of higher quality and novelty. In the second setting, DARLING achieves higher pass@1 (solution quality) and pass@k (solution variety). Most strikingly, explicitly optimizing for diversity catalyzes exploration in online RL, which manifests itself as higher-quality responses.
title Jointly Reinforcing Diversity and Quality in Language Model Generations
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2509.02534