Actor-Critic Methods in Reinforcement Learning - An Introduction

Actor-Critic methods are a family of reinforcement learning algorithms that combine the benefits of value-based and policy-based approaches: an actor learns which actions to take, while a critic learns to judge how good those actions were and feeds that judgement back so the actor’s learning signal is far less noisy. This post builds the idea from the ground up: why pure policy gradients are noisy, how a baseline fixes that for free, and why the critic is really just a learned, state-dependent baseline.

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