Forming Classes from Categories

The idea is to remove distinctions from the comprehensive taxonomy until a suitable number of classes is obtained. Figure [*] is thus a reduced version of Figure [*].

Figure: Overview of the Classification of Queries
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The second and third lines concern output. Only the prescence or absence of explicit attributes and timestamps are distinguished, leading to three categories. The last three lines concern valid-time selection (non-temporal selection is disregarded). Comparison operators may be duration-based or not; arguments be of either event, interval, or element type; and the arguments may or may not derive from valid times of tuples.