Ppo

PPO — Proximal Policy Optimization PPO is a reinforcement learning algorithm from OpenAI (Schulman et al., 2017) that became the default workhorse for RLHF — it’s what trained InstructGPT and the original ChatGPT. Core Idea Policy gradient methods are unstable because a single large update can collapse the policy. PPO fixes this by staying close to the previous policy on each update — the “proximal” part. It does this with a clipped surrogate objective: ...