Post-training Large Language Models for Diverse High-Quality Responses

Fuente: arXiv
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Hauptverfasser: Chen, Yilei, Chakraborty, Souradip, Wolf, Lorenz, Paschalidis, Yannis, Pacchiano, Aldo
Format: Preprint
Veröffentlicht: 2025
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author Chen, Yilei
Chakraborty, Souradip
Wolf, Lorenz
Paschalidis, Yannis
Pacchiano, Aldo
author_facet Chen, Yilei
Chakraborty, Souradip
Wolf, Lorenz
Paschalidis, Yannis
Pacchiano, Aldo
contents Reinforcement learning (RL) has emerged as a popular method for post-training large language models (LLMs). While improving the model's performance on downstream tasks, it often reduces the model's output diversity, leading to narrow, canonical responses. Existing methods to enhance diversity are limited, either by operating at inference time or by focusing on surface-level differences. We propose a novel training method named DQO (Diversity Quality Optimization) based on determinantal point processes (DPPs) to jointly optimize LLMs for quality and semantic diversity. Our approach samples and embeds a group of responses for each prompt, then uses the determinant of a kernel-based similarity matrix to measure diversity as the volume spanned by the embeddings of these responses. DQO is flexible and can be applied on top of existing RL algorithms. Experiments across instruction-following, summarization, story generation, and reasoning tasks demonstrate that our method substantially improves semantic diversity without sacrificing model quality.
format Preprint
id arxiv_https___arxiv_org_abs_2509_04784
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Post-training Large Language Models for Diverse High-Quality Responses
Chen, Yilei
Chakraborty, Souradip
Wolf, Lorenz
Paschalidis, Yannis
Pacchiano, Aldo
Computation and Language
Artificial Intelligence
Reinforcement learning (RL) has emerged as a popular method for post-training large language models (LLMs). While improving the model's performance on downstream tasks, it often reduces the model's output diversity, leading to narrow, canonical responses. Existing methods to enhance diversity are limited, either by operating at inference time or by focusing on surface-level differences. We propose a novel training method named DQO (Diversity Quality Optimization) based on determinantal point processes (DPPs) to jointly optimize LLMs for quality and semantic diversity. Our approach samples and embeds a group of responses for each prompt, then uses the determinant of a kernel-based similarity matrix to measure diversity as the volume spanned by the embeddings of these responses. DQO is flexible and can be applied on top of existing RL algorithms. Experiments across instruction-following, summarization, story generation, and reasoning tasks demonstrate that our method substantially improves semantic diversity without sacrificing model quality.
title Post-training Large Language Models for Diverse High-Quality Responses
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2509.04784