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Classification

Classification. Grouping of like objects (entities, documents, products) Aboutness Collocation Taxonomy, Ontology, Schema, Systematics, Nomenclature,…. Classification History. Aristotle Category (Greek kategoría, accusation, attribution). E.g., Blood-bearing animals

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Classification

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  1. Classification • Grouping of like objects (entities, documents, products) • Aboutness • Collocation • Taxonomy, Ontology, Schema, Systematics, Nomenclature,….

  2. Classification History • Aristotle • Category • (Greek kategoría, accusation, attribution). • E.g., Blood-bearing animals • Four-footed animals, live birth • Birds • Egg-laying 4-footed animals (reptiles + amphibians) • Whales and their allies • Fishes • Carl Von Linne, (Linnaeus)

  3. Linnaean taxonomy

  4. Classification History • Aristotle - Classical Theory of Categories • things are categorized together based on what they have in common (properties) • Clear boundaries, hierarchy mirroring the actual world • Unchallenged until mid-19th c.

  5. Cracks in Classical Theory • Research in logic and psychology • Wittgenstein, 1953, family resemblances • Austin, 1961, studied words • Zadeh, 1965, fuzzy set theory • Lonsbury, 1965, family kinship • Rosch, 1973-early 1980’s, prototype theory • Ad hoc categories

  6. Human Categorization • Anytime we see something as a kind of thing, for example, a tree, we are categorizing. Whenever we reason about kinds of things – chairs, nations, illnesses, emotions, any kind of things at all – we are employing categories. Lakoff, George (1987). Women, Fire, and Dangerous Things. Chicago, IL: University of Chicago Press.

  7. Langridge • Purpose • Facilitates everyday life • Choice of classification is always related to purpose • Natural vs. Artificial classification • What is the difference? • Situational classification

  8. Langridge • Same object may be classified in many ways • No absolute classification • Classifications are made not discovered

  9. Langridge • Classification of phenomena not limited to sciences • Knowledge classification • Knowledge organization • Is there a boundary? • Bibliographic classification • Knowledge after it has been embodied • theme

  10. Classification • Used a multitude of places and environments: • Supermarkets • Knowledge bases of expert systems • Institutional archives & repositories • Digital & physical libraries (collocation and stack arrangement) • Web pages -- design of menus for interactive searching • Etc…

  11. Classification Advantages • Context, grouping • Overview of the scope of a service • Browsing, serendipity • Broadening and narrowing a search (hierarchy subject tree) • Browsing a directory-type structure is user friendly • Look for related items not previously identified as relevant - serendipity • Partitioning / Segmenting (facets)

  12. Classification Advantages continued • Multilingual access • Same semantics across databases • Interoperability on agreed classification schemes • Permanence • Known by users • Available in machine readable form

  13. Classification Criticisms • Logical division splits related materials • Illogical division of classes • Difficulties and delay in adding new topics

  14. BioMedical Classification systems • UMLS, MesH • SNOMED CT • LOINC • ICD • GO • OBO Foundry • Nation Center for Biomedical Ontology

  15. Structure of Classification Schemes • Structure • Enumerative (a list) • Faceted (parts) • Hierarchical (structured from general to specific)

  16. Enumerative • History • Art history • Medieval history • Roman history • Scientific history • http://www.yahoo.com • http://www.froogle.com

  17. Faceted • Faceted classification works on an “analytico-synthetic principle” • System: Fundamental concepts are analyzed and grouped together into facets • Concepts are combined or “synthesized” as necessary to form more complex subjects

  18. Facets • AAT (Art and Architecture Thesaurus) • Physical attributes (size, shape, texture) • Styles and periods • Agents • Materials • Objects (chair, painting) • http://www.getty.edu/research/conducting_research/vocabularies/aat/about.html • Ornate style • On-line Shopping (Best Buy)

  19. Hierarchical • Super-ordinate and sub-ordinate • Genus/species • Class/member More flexible application in classification systems than in terminological tools (thesauri, ontologies, etc.) • Example -- UMLS/MeSH

  20. Hierarchical example w/BEER BEER Ale Bitter Brown Ale India Pale Ale Mild Pale Ale Lager Pilsner Porter Stout Sweet Stout Dry Stout Imperial Stout

  21. MeSH Tree Browser • Explore Mesh (use brain cancer) • Mesh Tree Browser

  22. What does the future hold • Hint… • Databases evolved from hierarchical to network, to relational. • Maybe Classification is evolving from hierarchical to faceted (somewhat analogous to relational).

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