Zero-shot transfer learning for dialogue state tracking (DST) enables us to handle a variety of task-oriented dialogue domains without the expense of collecting in-domain data. In this work, we propose to transfer the \textit{cross-task} knowledge from general question answering (QA) corpora for the zero-shot DST task. Specifically, we propose TransferQA, a transferable generative QA model that seamlessly combines extractive QA and multi-choice QA via a text-to-text transformer framework, and tracks both categorical slots and non-categorical slots in DST. In addition, we introduce two effective ways to construct unanswerable questions, namely, negative question sampling and context truncation, which enable our model to handle "none" value slots in the zero-shot DST setting. The extensive experiments show that our approaches substantially improve the existing zero-shot and few-shot results on MultiWoz. Moreover, compared to the fully trained baseline on the Schema-Guided Dialogue dataset, our approach shows better generalization ability in unseen domains.

本论文提出了TransferQA，一个可转移的生成式问答模型，它通过文本到文本转换框架无缝地结合了抽取式问答和多选式问答，有效地处理了零-shot DST任务中的分类和非分类插槽，并介绍了两种构建无法回答的问题的有效方法，即负面问题抽样和上下文截断。经过实验证明，在MultiWoz上，我们的方法显著改善了现有的零-shot和少-shot结果，与Schema-Guided Dialogue数据集上的全面训练基线相比，我们的方法在未知领域中表现出更好的泛化能力。

通过跨任务转移实现零样本对话状态跟踪