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?'' Using the schema of Figure [*] (this schema will be used in the remainder of the document unless explicitly stated otherwise), this query is in the category shown next (with no valid-time selection).

(None, Element, Union) // (=, 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 38×8 = 304 categories. Adding a single valid-time operator while assuming orthogonality yields 8208 categories!

As a result, it becomes necessary to create classes of categories which then may be used for classifying the 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, Union) / (*,*,*) / (=, Constant) (=, Constant)

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