In general, there are two types of dialogue systems: the task-oriented dialogue system and the non-task-oriented or chat dialogue system. In recent years, chat dialogue systems have received much attention mainly because of the advances in automatic knowledge acquisition from the web. Nevertheless, few studies are dedicated to the error analysis of chat dialogue systems. This is in contrast with the many error-analysis-related studies on task-oriented dialogue systems. An error in a chat dialogue system can lead to the dialogue breakdown, where users are no longer willing to continue the conversation. Therefore, error analysis is crucial in such systems. However, it is difficult to analyze errors in chat dialogue systems because of the complex internal structures of the systems. In the present study, we analyze and categorize the errors in a text chat dialogue system on the basis of the surface form of the conversations. We construct a chat dialogue corpus between a chat system and users and analyze the dialogue breakdowns included in the corpus.
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