Abstract
This paper describes some time interval operations and their application, in conjunction with the research and development project for a video database system “Heijo”. Retrieving meaningful video fragments from video databases is a challenging issue. Heijo can process such queries by combining simple indices constructed on each video data. To this end, three kinds of operations on time intervals, namely, intersection, union, and joint operations are proposed. In addition, five kinds of time axes and categorization of video data based on the time axes are introduced so that we can distinguish video data by their contents.