1. Information Retrieval and Knowledge Management Research LabNational Engineering Research Center for E‐Learning, Central China Normal University Wuhan China
2. School of Computer and Information EngineeringHubei Normal University Huangshi China
3. Information Retrieval and Knowledge Management Research LabSchool of Information Technology, York University Toronto ON Canada
4. Information Retrieval and Knowledge Management Research LabSchool of Computer, Central China Normal University Wuhan China
5. Information Retrieval and Knowledge Management Research LabSchool of Information Management, Central China Normal University Wuhan China