Faceted classification

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A faceted classification system allows the assignment of multiple classifications to an object, allowing searching and browsing of related information through several classes. Elements may include subject, geographical, temporal and form of an item.

In a faceted classification, subjects are divided into facets (aspects), and class numbers are synthesised from the classifications. Analytico-synthetic method is much more powerful than more traditional hierarchical enumerative schemes such as the Library of Congress classification, Dewey Decimal Classification or Chinese Library Classification, but can result in much longer class numbers. It has been a major theoretical influence to classification researchers.

The Colon classification developed by S. R. Ranganathan and the Universal Decimal Classification are the two most prominent examples of faceted classification in the physical world, where for many years this approach to classification was thought of as something complicated, difficult to understand and exotic. The rules for generating class numbers are a key part of this complication, but they are necessary to make sure each item gets its proper spot on the bookshelf.

In the online world, faceted classification becomes much more useful because it is not bound by this constraint. It makes information access useful, by providing multiple navigational paths to any one item of information. For instance, a restaurant guide can classify a restaurant by location, price, rating, awards, ambience, and amenities. A user can navigate through any of these facets, combining them in any way to reach exactly the desired restaurant. In contrast to a folksonomy, the information in each of the facets can be organized into a hierarchy (for instance, the location facet could be divided by state, then cities, then neighborhoods).

Faceted classification is also used in software engineering to support software reuse.

[edit] Navigation

Faceted navigation is provided by a navigation system which offers multiple facets of navigation to a single piece of information. This is done by using faceted classification to group bits and pieces of information together.

"A faceted classification scheme may be implemented in an advanced search interface and/or as part of the navigational interface for browsing"

– Kathryn La Barre, Use of Faceted Classification