Gunrock is the winner of the 2018 Amazon Alexa Prize, as evaluated by coherence and engagement from both real users and Amazon-selected expert conversationalists. We focus on understanding complex sentences and having in-depth conversations in open domains. In this paper, we introduce some innovative system designs and related validation analysis. Overall, we found that users produce longer sentences to Gunrock, which are directly related to users' engagement (e.g., ratings, number of turns). Additionally, users' backstory queries about Gunrock are positively correlated to user satisfaction. Finally, we found dialog flows that interleave facts and personal opinions and stories lead to better user satisfaction.

A team of students from the University of California, Davis, has won the global 2018 Amazon Alexa Prize and a $500,000 prize for creating a "chatbot" that can converse engagingly with humans on a range of topics such as entertainment, sports, politics, technology and fashion. The prize was announced today (Nov. Zhou Yu, an assistant professor in the College of Engineering's Department of Computer Science, led the team of 11 graduate and undergraduate students to victory. "When our team first came together, we were competing against teams that had already participated in this challenge," Yu said. "For us, it was our first time competing. Now, we are the best in the world in social conversational systems. They really came together and made this happen."