Cameron Wolfe Questions PPO Ratio Derivation in Tweet

Cameron R. Wolfe, Staff Research Scientist at Netflix and author of the Deep Learning Focus Substack, posted on X about the policy importance ratio in PPO. He observes that typical explainers begin with a vanilla policy gradient expression and then move directly to PPO. The post points out that PPO is usually presented as a loss multiplying an importance ratio by the advantage. Wolfe asks where that ratio originates and indicates the attached text traces its derivation from the underlying policy gradient steps.