We present the first class of policy-gradient algorithms that work with both state-value and policy function-approximation, and are guaranteed to converge under off-policy training. Our solution targets problems in reinforcement learning where the action representation adds to the-curse-of-dimensionality; that is, with continuous or large action sets, thus making it infeasible to estimate state-action value functions (Q functions). Using state-value functions helps to lift the curse and as a result naturally turn our policy-gradient solution into classical Actor-Critic architecture whose Actor uses state-value function for the update. Our algorithms, Gradient Actor-Critic and Emphatic Actor-Critic, are derived based on the exact gradient of averaged state-value function objective and thus are guaranteed to converge to its optimal solution, while maintaining all the desirable properties of classical Actor-Critic methods with no additional hyper-parameters. To our knowledge, this is the first time that convergent off-policy learning methods have been extended to classical Actor-Critic methods with function approximation.

我们提出了第一种同时适用于状态值和策略函数逼近的政策梯度算法，保证在离线学习下收敛，解决了动作表示问题带来的高维“诅咒”问题，这些算法是基于基于平均状态值函数目标的渐变高演员-评论家和强调梯度的高演员-评论家推导而来，能够保持所有经典Actor-Critic方法的优点，并且在功能逼近方面被证明是可收敛的。

基于离线训练和函数近似的收敛演员-评论家算法