What is an ontology? An inductive explanation.

What is an ontology? An inductive explanation.

Term list:

  • word list
    • list of used terms
    • stemming?
    • e.g.
      • back in book index
      • folksonomy
  • index
    • prefered label
    • alternative label
    • deprecated label
  • glossary
    • related
  • thesaurus
    • broader term
    • narrower term
    • conceptGroup
  • taxonomy
    • class - subclass
    • class vs. instance
    • classes are defined by features (feature: charakteristisches Merkmal)
    • intension vs. extension
    • class tree or concept lattice (Begriffsverband)
    • "light weight ontolgy"
  • ontology
    • classes are defined by predefined rule types
      • class axioms
      • classification rules
  • rule based ontology
    • first order logic
    • fully rule based system
    • arbitrary class definitions

Each term is a specialization of it's predecessor.

  • In fact we have a built a taxonomy.
  • According to this term list an ontology is a sophisticated taxonomy.

classification agenda

  • top down
  • for each subclass classify if all features are given
  • extension shrinks

Meta terms

  • terms (classes, sets) are defined by features (intension)
  • features define class tree
  • examples (extension)
  • intension vs. extension

from native format to XML to semantic

  • free format
    • CSV
  • XML
    • data are parsed according to a uniform syntax: you don't need to write a parser any more!
    • underlying meta data model: XML tree, i.e. nested tagged content
    • XML Schema allows for validating syntax of data
    • language XSLT allows for transforming syntax, i.e. XML trees into XML trees
    • schema check = analyse syntax of data = check coherence with grammar
    • understanding of the data is open / 2b defined / undefined: bug or feature?
  • semantic
    • data are interpreted according to an uniform knowledge representation: you don't need to write an inferencing engine any more!
    • underlying data model: directed labeled graph
    • schema part of an ontology allows for validating semantic (model conformity) of data
    • description logic allows for
      • classifying individuals
      • checking soundness of a classification system
    • rule languages allow for model transformations, i.w. translations of data models into data models
    • semantic check = analyze understanding of data = check for coherence with a set of logical rules
    • ontology schema allows for checking logical soundness (Widerspruchsfreiheit)