Overview and Naming of Categories

Each query has a single output component, zero or more valid-time selection components (one per such operator), and zero or more non-temporal selection-based components (one per such operator). The taxonomy is summarized in Figure [*]. There, the names introduced in the taxonomy are used along with punctuation in order to name a category.

Figure: Overview of the Taxonomy used for Naming Categories
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To exemplify the use of Figure [*] for naming categories, consider the query ``When was Ed Manager of the Toy Department.'' This query is in the category shown next (with no valid-time selection).

(None, Element, Derived) // (=, Constant) (=, Constant)

It may be observed that the taxonomy gives rise to a large number of categories. For example, assuming a single non-temporal operator and no valid-time operators, there are 20×8 = 160 categories. Adding a single valid-time operator while assuming orthogonality yields an additional 4320 categories!

As a result, it becomes necessary to create classes of categories which then may be used for clasifying the benchmark queries.

One approach would be to name a class of categories of queries, by simply replacing one or more of the entries with the Kleene star (``*''), e.g.,

(None, Element, Derived) / (*,*,*) / (=, Constant)

The above query category would be in this class. In the next section, we define the classes to be used in the benchmark.