TR2-D2: Tree Search Guided Trajectory-Aware Fine-Tuning for Discrete Diffusion

Fuente: arXiv
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Hauptverfasser: Tang, Sophia, Zhu, Yuchen, Tao, Molei, Chatterjee, Pranam
Format: Preprint
Veröffentlicht: 2025
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author Tang, Sophia
Zhu, Yuchen
Tao, Molei
Chatterjee, Pranam
author_facet Tang, Sophia
Zhu, Yuchen
Tao, Molei
Chatterjee, Pranam
contents Reinforcement learning with stochastic optimal control offers a promising framework for diffusion fine-tuning, where a pre-trained diffusion model is optimized to generate paths that lead to a reward-tilted distribution. While these approaches enable optimization without access to explicit samples from the optimal distribution, they require training on rollouts under the current fine-tuned model, making them susceptible to reinforcing sub-optimal trajectories that yield poor rewards. To overcome this challenge, we introduce TRee Search Guided TRajectory-Aware Fine-Tuning for Discrete Diffusion (TR2-D2), a novel framework that optimizes reward-guided discrete diffusion trajectories with tree search to construct replay buffers for trajectory-aware fine-tuning. These buffers are generated using Monte Carlo Tree Search (MCTS) and subsequently used to fine-tune a pre-trained discrete diffusion model under a stochastic optimal control objective. We validate our framework on single- and multi-objective fine-tuning of biological sequence diffusion models, highlighting the overall effectiveness of TR2-D2 for reliable reward-guided fine-tuning in discrete sequence generation.
format Preprint
id arxiv_https___arxiv_org_abs_2509_25171
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle TR2-D2: Tree Search Guided Trajectory-Aware Fine-Tuning for Discrete Diffusion
Tang, Sophia
Zhu, Yuchen
Tao, Molei
Chatterjee, Pranam
Machine Learning
Biomolecules
Reinforcement learning with stochastic optimal control offers a promising framework for diffusion fine-tuning, where a pre-trained diffusion model is optimized to generate paths that lead to a reward-tilted distribution. While these approaches enable optimization without access to explicit samples from the optimal distribution, they require training on rollouts under the current fine-tuned model, making them susceptible to reinforcing sub-optimal trajectories that yield poor rewards. To overcome this challenge, we introduce TRee Search Guided TRajectory-Aware Fine-Tuning for Discrete Diffusion (TR2-D2), a novel framework that optimizes reward-guided discrete diffusion trajectories with tree search to construct replay buffers for trajectory-aware fine-tuning. These buffers are generated using Monte Carlo Tree Search (MCTS) and subsequently used to fine-tune a pre-trained discrete diffusion model under a stochastic optimal control objective. We validate our framework on single- and multi-objective fine-tuning of biological sequence diffusion models, highlighting the overall effectiveness of TR2-D2 for reliable reward-guided fine-tuning in discrete sequence generation.
title TR2-D2: Tree Search Guided Trajectory-Aware Fine-Tuning for Discrete Diffusion
topic Machine Learning
Biomolecules
url https://arxiv.org/abs/2509.25171