Taxonomy is the practice and science of classification. The word comes from the Greek τάξις, taxis, 'order' + νόμος, nomos, 'law' or 'science'. Taxonomies, or taxonomic schemes, are composed of taxonomic units known as taxa (singular taxon), or kinds of things that are arranged frequently in a hierarchical structure, typically related by subtype-supertype relationships, also called parent-child relationships. In such a subtype-supertype relationship the subtype kind of thing has by definition the same constraints as the supertype kind of thing plus one or more additional constraints. For example, car is a subtype of vehicle. So any car is also a vehicle, but not every vehicle is a car. So, a thing needs to satisfy more constraints to be a car than to be a vehicle.
Originally the term taxonomy referred to the classifying of living organisms (now known as alpha taxonomy); however, the term is now applied in a wider, more general sense and now may refer to a classification of things, as well as to the principles underlying such a classification.
Almost anything — animate objects, inanimate objects, places, concepts, events, properties, and relationships — may be classified according to some taxonomic scheme.
The term taxonomy may also apply to relationship schemes other than parent-child hierarchies, such as network structures with other types of relationships. taxonomies may include single children with multi-parents, for example, "Car" might appear with both parents "Vehicle" and "Steel Mechanisms"; to some however, this merely means that 'car' is a part of several different taxonomies.
A taxonomy might also be a simple organization of kinds of things into groups, or even an alphabetical list. However, the term vocabulary is more appropriate for such a list. In current usage within "Knowledge Management", taxonomies are seen as less broad than ontologies as ontologies apply a larger variety of relation types.
Mathematically, a hierarchical taxonomy is a tree structure of classifications for a given set of objects. It is also named Containment hierarchy. At the top of this structure is a single classification, the root node, that applies to all objects. Nodes below this root are more specific classifications that apply to subsets of the total set of classified objects. So for instance, in common schemes of scientific classification of organisms, the root is called "Organism" followed by nodes for the taxonomic ranks: Domain, kingdom, phylum, class, etc.
Taxonomy and mental classification
Some have argued that the human mind naturally organizes its knowledge of the world into such systems. This view is often based on the epistemology of Immanuel Kant. Anthropologists have observed that taxonomies are generally embedded in local cultural and social systems, and serve various social functions. Perhaps the most well-known and influential study of folk taxonomies is Émile Durkheim's The Elementary Forms of Religious Life.
In phylogenetic taxonomy (or cladistic taxonomy), organisms can be classified by clades, which are based on evolutionary grouping by ancestral traits. By using clades as the criteria for separation, cladistic taxonomy, using cladograms, can categorize taxa into unranked groups.
Other taxonomies, such as those analyzed by Durkheim and Lévi-Strauss, are sometimes called folk taxonomies to distinguish them from scientific taxonomies that claim to be disembedded from social relations and thus objective and universal.
The neologism folksonomy should not be confused with "folk taxonomy" (though it is obviously a contraction of the two words). Those who support scientific taxonomies have recently criticized folksonomies by dubbing them "fauxonomies" (French word "faux" means "false").
The phrase "enterprise taxonomy" is used in business to describe a very limited form of taxonomy used only within one organization. An example would be a certain method of classifying trees as "Type A", "Type B" and "Type C" used only by a certain lumber company for categorising log shipments.
- Bloom's Taxonomy
- Carolus Linnaeus, the father of systematics
- Celestial Emporium of Benevolent Recognition, a fictional Chinese encyclopedia with an "impossible" taxonomic scheme.
- Cladistics, the most prominent of several forms of phylogenetic systematics
- Gellish English dictionary / Taxonomy, in which the concepts are arranged as a subtype-supertype hierarchy.
- History of plant systematics
- Jean-Baptiste Lamarck
- Knowledge representation
- Linnaean taxonomy
- Phylogenetic Carl Woese demonstrates a new Taxon method to show evolution via chromosomal methods.
- Scientific classification
- SOLO Taxonomy
- Species problem
- Utter freedom via tagging and social constructs
- Wikispecies Main Page
- Integrated Taxonomic Information System
- Taxonomy Browser of National Center for Biotechnology Information
- Library of Taxonomy Resources
- Metadata? Thesauri? Taxonomies? Topic Maps! - Making sense of it all
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