This lecture transitions from imitation learning to the foundations of Reinforcement Learning from Human Feedback (RLHF) and its modern extensions like Direct Preference Optimization (DPO). The instructor begins with a recap of behavior cloning and DAGGER, connecting them to recent advancements where reinforcement learning (RL) methods enable systems such as ChatGPT to learn from human preferences.
Key points:
- Behavior Cloning (BC): Reduces RL to supervised learning by learning direct mappings from states to actions using expert demonstrations.
- DAGGER (Dataset Aggregation): Improves upon BC by incorporating expert feedback iteratively to correct policy drift due to distribution mismatch.
- RLHF: Combines supervised fine-tuning with human feedback to align large models like ChatGPT.