Preference-Based Alignment of Discrete Diffusion Models

Fuente: arXiv
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Auteurs principaux: Borso, Umberto, Paglieri, Davide, Wells, Jude, Rocktäschel, Tim
Format: Preprint
Publié: 2025
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author Borso, Umberto
Paglieri, Davide
Wells, Jude
Rocktäschel, Tim
author_facet Borso, Umberto
Paglieri, Davide
Wells, Jude
Rocktäschel, Tim
contents Diffusion models have achieved state-of-the-art performance across multiple domains, with recent advancements extending their applicability to discrete data. However, aligning discrete diffusion models with task-specific preferences remains challenging, particularly in scenarios where explicit reward functions are unavailable. In this work, we introduce Discrete Diffusion DPO (D2-DPO), the first adaptation of Direct Preference Optimization (DPO) to discrete diffusion models formulated as continuous-time Markov chains. Our approach derives a novel loss function that directly fine-tunes the generative process using preference data while preserving fidelity to a reference distribution. We validate D2-DPO on a structured binary sequence generation task, demonstrating that the method effectively aligns model outputs with preferences while maintaining structural validity. Our results highlight that D2-DPO enables controlled fine-tuning without requiring explicit reward models, making it a practical alternative to reinforcement learning-based approaches. Future research will explore extending D2-DPO to more complex generative tasks, including language modeling and protein sequence generation, as well as investigating alternative noise schedules, such as uniform noising, to enhance flexibility across different applications.
format Preprint
id arxiv_https___arxiv_org_abs_2503_08295
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Preference-Based Alignment of Discrete Diffusion Models
Borso, Umberto
Paglieri, Davide
Wells, Jude
Rocktäschel, Tim
Machine Learning
Artificial Intelligence
Diffusion models have achieved state-of-the-art performance across multiple domains, with recent advancements extending their applicability to discrete data. However, aligning discrete diffusion models with task-specific preferences remains challenging, particularly in scenarios where explicit reward functions are unavailable. In this work, we introduce Discrete Diffusion DPO (D2-DPO), the first adaptation of Direct Preference Optimization (DPO) to discrete diffusion models formulated as continuous-time Markov chains. Our approach derives a novel loss function that directly fine-tunes the generative process using preference data while preserving fidelity to a reference distribution. We validate D2-DPO on a structured binary sequence generation task, demonstrating that the method effectively aligns model outputs with preferences while maintaining structural validity. Our results highlight that D2-DPO enables controlled fine-tuning without requiring explicit reward models, making it a practical alternative to reinforcement learning-based approaches. Future research will explore extending D2-DPO to more complex generative tasks, including language modeling and protein sequence generation, as well as investigating alternative noise schedules, such as uniform noising, to enhance flexibility across different applications.
title Preference-Based Alignment of Discrete Diffusion Models
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2503.08295