DoMinO: Discrete Flow-Matching Policy Optimization

Apr 1, 2026 · 1 min read
projects

Role: Project Co-Lead · Northwestern University (Remote) · Feb 2026 – Apr 2026

DoMinO is a reinforcement learning framework for fine-tuning discrete flow-matching models toward a reward.

What I did

  • Co-developed the framework. DoMinO formulates discrete flow-matching inference as an inner Markov decision process, which enables exact trajectory log-likelihood optimization.
  • Implemented the fine-tuning methods. REINFORCE- and PPO-based fine-tuning with cross-entropy and generalized KL regularization, to mitigate reward hacking and preserve sequence naturalness.
  • Evaluated on biological sequence design. On regulatory DNA and protein design, DoMinO outperformed prior state-of-the-art baselines by 10.6% on DNA predicted activity and 15.4% on protein pred-ddG.

Paper: Discrete Flow Matching Policy Optimization. See also the research overview.

Po-Chung (Bryan) Hsieh
Authors
M.S. Student in Electrical and Computer Engineering
I am an M.S. student in Electrical and Computer Engineering at UC San Diego, with a B.S. in Electrical Engineering from National Taiwan University. I build AI agents and reinforcement learning methods for scientific discovery, including multi-agent systems for biomedical feature discovery and policy optimization for discrete generative models, and I previously worked as an LLM engineer intern at the Inventec Artificial Intelligence Center.