Abstract: Recent dialogue state tracking works have focused on the hybrid approach to balance the two extreme methods(i.e.,over-reliance on ontology and complete abandoning ontology).However,some special phenomena are ignored in these works.For instant,value sharing and recommendation acceptance.In addition,the widely used slot gate mechanism makes it difficult for the model to process slots in parallel and the mechanism also propagates errors to the slot value generation steps.This paper proposes a new hybrid approach that deals with four different phenomena,namely diverse value,unseen value,value sharing and recommendation acceptance.By modifying the candidate value set and the model input,our model can parallelly process slots in one step and no longer depend on the slot gate.Experimental results indicate that the model achieves 57.7% and 59.5% joint goal accuracy on the English dataset MultiWOZ 2.2 and 2.3,respectively,and reaches 68.1% on the Chinese dataset RiSAWOZ,with only 10ms infer time.Finally,the robustness of the model is analyzed.The results on MultiWOZ 2.2 show that the joint target accuracy rate is 55.4% when the recommendation error rate reaches 15%.

Key words: Task-oriented dialogue system, Dialogue state tracking, BERT, Parallel computing, Schema-guided dialogue