Anti-Overestimation Dialogue Policy Learning for Task-Completion Dialogue System

Chang Tian, Wenpeng Yin, Marie-Francine Moens


Abstract
A dialogue policy module is an essential part of task-completion dialogue systems. Recently, increasing interest has focused on reinforcement learning (RL)-based dialogue policy. Its favorable performance and wise action decisions rely on an accurate estimation of action values. The overestimation problem is a widely known issue of RL since its estimate of the maximum action value is larger than the ground truth, which results in an unstable learning process and suboptimal policy. This problem is detrimental to RL-based dialogue policy learning. To mitigate this problem, this paper proposes a dynamic partial average estimator (DPAV) of the ground truth maximum action value. DPAV calculates the partial average between the predicted maximum action value and minimum action value, where the weights are dynamically adaptive and problem-dependent. We incorporate DPAV into a deep Q-network as the dialogue policy and show that our method can achieve better or comparable results compared to top baselines on three dialogue datasets of different domains with a lower computational load. In addition, we also theoretically prove the convergence and derive the upper and lower bounds of the bias compared with those of other methods.
Anthology ID:
2022.findings-naacl.43
Volume:
Findings of the Association for Computational Linguistics: NAACL 2022
Month:
July
Year:
2022
Address:
Seattle, United States
Venues:
Findings | NAACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
565–577
Language:
URL:
https://aclanthology.org/2022.findings-naacl.43
DOI:
10.18653/v1/2022.findings-naacl.43
Bibkey:
Cite (ACL):
Chang Tian, Wenpeng Yin, and Marie-Francine Moens. 2022. Anti-Overestimation Dialogue Policy Learning for Task-Completion Dialogue System. In Findings of the Association for Computational Linguistics: NAACL 2022, pages 565–577, Seattle, United States. Association for Computational Linguistics.
Cite (Informal):
Anti-Overestimation Dialogue Policy Learning for Task-Completion Dialogue System (Tian et al., Findings 2022)
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PDF:
https://aclanthology.org/2022.findings-naacl.43.pdf