Negative Momentum-Based Policy Gradient for Reinforcement Learning
摘要
Stochastic optimization algorithms, particularly stochastic policy gradient (SPG), report significant success in reinforcement learning (RL). Nevertheless, up to now, how to speedily acquire an optimal solution for RL is still a challenge. To tackle this issue, this work develops a fast SPG algorithm from the perspective of utilizing a momentum, coined SPG-NM. Specifically, in SPG-NM, a novel type of negative momentum (NM) technique is applied to the classical SPG algorithm. Different from the existing NM techniques, we have adopted a few hyper-parameters in our SPG-NM algorithm. Moreover, the computational complexity is nearly the same as the modern SPG-type algorithms, e.g., accelerated policy gradient (APG), which equips SPG with Nesterov’s accelerated gradient (NAG). We evaluate the resulting algorithm on a classical task, the Markov decision process (MDP). Numerical results in different tasks demonstrate a faster convergence rate of the resulting algorithm by comparing state-of-the-art algorithms, which confirms the positive impact of NM in accelerating SPG for RL. Also, numerical experiments under different settings confirm the robustness of our SPG-NM algorithm for certain crucial hyper-parameters, which make the user feel free in practice.