The Sufficiency of Off-Policyness and Soft Clipping: PPO Is Still Insufficient According to an Off-Policy Measure

Xing Chen, Dongcui Diao, Hechang Chen, Hengshuai Yao, Haiyin Piao, Zhixiao Sun, Zhiwei Yang, Randy Goebel, Bei Jiang, Yi Chang

AAAI 2023 pp. 7078-7086

doi:10.1609/AAAI.V37I6.25864 /aaai/2023/chen2023aaai-sufficiency/

Abstract

The popular Proximal Policy Optimization (PPO) algorithm approximates the solution in a clipped policy space. Does there exist better policies outside of this space? By using a novel surrogate objective that employs the sigmoid function (which provides an interesting way of exploration), we found that the answer is "YES", and the better policies are in fact located very far from the clipped space. We show that PPO is insufficient in "off-policyness", according to an off-policy metric called DEON. Our algorithm explores in a much larger policy space than PPO, and it maximizes the Conservative Policy Iteration (CPI) objective better than PPO during training. To the best of our knowledge, all current PPO methods have the clipping operation and optimize in the clipped policy space. Our method is the first of this kind, which advances the understanding of CPI optimization and policy gradient methods. Code is available at https://github.com/raincchio/P3O.

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Cite

Text

Chen et al. "The Sufficiency of Off-Policyness and Soft Clipping: PPO Is Still Insufficient According to an Off-Policy Measure." AAAI Conference on Artificial Intelligence, 2023. doi:10.1609/AAAI.V37I6.25864

Markdown

[Chen et al. "The Sufficiency of Off-Policyness and Soft Clipping: PPO Is Still Insufficient According to an Off-Policy Measure." AAAI Conference on Artificial Intelligence, 2023.](https://mlanthology.org/aaai/2023/chen2023aaai-sufficiency/) doi:10.1609/AAAI.V37I6.25864

BibTeX

@inproceedings{chen2023aaai-sufficiency,
  title     = {{The Sufficiency of Off-Policyness and Soft Clipping: PPO Is Still Insufficient According to an Off-Policy Measure}},
  author    = {Chen, Xing and Diao, Dongcui and Chen, Hechang and Yao, Hengshuai and Piao, Haiyin and Sun, Zhixiao and Yang, Zhiwei and Goebel, Randy and Jiang, Bei and Chang, Yi},
  booktitle = {AAAI Conference on Artificial Intelligence},
  year      = {2023},
  pages     = {7078-7086},
  doi       = {10.1609/AAAI.V37I6.25864},
  url       = {https://mlanthology.org/aaai/2023/chen2023aaai-sufficiency/}
}