Data science 6th International Conference, ICDS 2019, Ningbo, China, May 15-20, 2019 : revised selected papers - He, Jing; Yu, Philip S.; Shi, Yong 1956-; Li, Xingsen; Xie, Zhijun; Huang, Guangyan; Cao, Jie; Xiao, Fu (Communications in computer and information science, 2020)