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Friday, July 17, 2009

Dynamic Taxonomies: Exploration of the Knowledge Base

Dynamic taxonomies can be used to browse and explore
the knowledge base in several ways. The preferred implementation
follows. The user is initially presented with a
tree representation of the initial taxonomy for the entire
knowledge base. Each concept label also has a count of
all the items classified under it—that is, the cardinality
of items(C) for all Cs. The initial user focus F is the
universe—all the items in the knowledge base.
In the simplest case, the user can then select a
concept C in the taxonomy and zoom on it. The zoom
operation changes the current state in two ways. First,
concept C is used to refine the current user focus F,
which becomes F items(C). Items not in the focus are
discarded. Second, the tree representation of the taxonomy
is modified in order to summarize the new focus.
All and only the concepts related to F are retained, and the
count for each retained concept C’ is updated to reflect the
number of items in the focus F that are classified under C’.
The reduced taxonomy is derived from the initial taxonomy
by pruning all the concepts not related to F, and
it is a conceptual summary of the set of documents
identified by F, exactly in the same way as the original
taxonomy was a conceptual summary of the universe. In
fact, the term dynamic taxonomy is used to indicate that
the taxonomy can dynamically adapt to the subset of the
universe on which the user is focusing, whereas traditional,
static taxonomies can only describe the entire
universe.

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