Policy Gradient Algorithm
Policy gradient algorithms are a class of reinforcement learning methods aiming to optimize a policy's parameters by directly maximizing expected cumulative rewards or more general utility functions. Current research focuses on improving sample efficiency, addressing challenges in high-dimensional spaces through function approximation techniques like linear regression and neural networks (e.g., Implicit Quantile Networks), and enhancing robustness and safety via methods such as variance reduction, risk-averse formulations (using Gini deviation), and probabilistic logic constraints. These advancements are significant for tackling complex real-world problems across diverse domains, including robotics, traffic control, and financial risk management, by enabling more efficient and reliable learning of optimal policies in challenging environments.