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Animating the reference terminology – showing classifiers at work

Animating the reference terminology – showing classifiers at work . Ed Cheetham, Principal Terminology Specialist. Introduction.

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Animating the reference terminology – showing classifiers at work

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  1. Animating the reference terminology – showing classifiers at work Ed Cheetham, Principal Terminology Specialist

  2. Introduction In addition to being hand-curated, SNOMED CT’s content is also (re-)organised, and its development quality assured, by the use of a description logic (DL) classifier.

  3. What is description logic? [Spackman 2008] Mathematical viewpoint: A family of logics characterized by Formal set-theoretic semantics Proofs of correctness and completeness of computation Proofs of algorithmic complexity (PSpace, NP-complete, NExpTime, etc) Knowledge representation viewpoint: A set of constructs for representing terminological knowledge Algorithms and their implementations for performing: Subsumption (testing pairs of expressions to see whether one is a subtype of the other & vice versa) Classification (structuring a set of expressions according to their subsumptionrelationships)

  4. DL-based classification – simply put... AND, OR, NOT, Roles, Role hierarchies Agree ‘set of constructs’ [operators, roles] Make certain properties of content formally explicit ‘Stated relationships Decide whether content is sufficiently defined in such terms Fully defined/primitive ‘Run’ classifier Defined – what are kinds of ‘me’? What am I a kind of? Primitive – what am I a kind of? Appendectomy Is_A Excision procedure AND Has_method=Excision AND Has_site=Appendix Appendectomy Fully defined Operation GI tract Fully defined Excision, Appendix Primitive

  5. Protégé: http://protege.stanford.edu/ Use does not indicate endorsement, but extremely valuable to illustrate points discussed

  6. Gephi: http://gephi.org/ Use does not indicate endorsement, but extremely valuable to illustrate points discussed

  7. Blue lines = stated and inferred Red lines = stated (removed as redundant) Green lines = inferred

  8. Conclusions DL-based classification is an intrinsic part of SNOMED CT development Necessary QA feature of large KR product Based on ‘what it is told’ and the expressivity of the other ‘constructs’, content is ruthlessly reorganised New ‘inferred’ knowledge (reclassification) Sometimes intended, sometimes unintended

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