  We study the adaption of soft actor-critic (SAC) from continuous action space
to discrete action space. We revisit vanilla SAC and provide an in-depth
understanding of its Q value underestimation and performance instability issues
when applied to discrete settings. We thereby propose entropy-penalty and
double average Q-learning with Q-clip to address these issues. Extensive
experiments on typical benchmarks with discrete action space, including Atari
games and a large-scale MOBA game, show the efficacy of our proposed method.
Our code is at:https://github.com/coldsummerday/Revisiting-Discrete-SAC.
