Conversational question answering (CQA) facilitates an incremental and interactive understanding of a given context, but building a CQA system is difficult for many domains due to the problem of data scarcity. In this paper, we introduce a novel method to synthesize data for CQA with various question types, including open-ended, closed-ended, and unanswerable questions. We design a different generation flow for each question type and effectively combine them in a single, shared framework. Moreover, we devise a hierarchical answerability classification (hierarchical AC) module that improves quality of the synthetic data while acquiring unanswerable questions. Manual inspections show that synthetic data generated with our framework have characteristics very similar to those of human-generated conversations. Across four domains, CQA systems trained on our synthetic data indeed show good performance close to the systems trained on human-annotated data.

本文提出了一种新的方法合成用于CQA的数据，其中包括开放式，封闭式和无法回答的问题，通过为每种问题类型设计不同的生成流程并将它们有效地结合在单个共享框架中，同时设计了分层回答分类模块，提高了合成数据的质量，手动检查发现我们的框架生成的合成数据具有非常类似于人类生成的对话的特征，在四个领域中，使用我们的合成数据训练的CQA系统的表现确实接近于使用人工注释数据训练的系统。

多类型对话式封闭和无法回答问题的问答生成