Towards Collaborative Environments for Ontology Construction and Sharing
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  • Ontologies play important roles in many application domains, such as semantic web, web service, bioinformatics, geological information processing, natural language processing…
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Towards Collaborative Environments for Ontology Construction and Sharing Towards Collaborative Environments for Ontology Construction and Sharing Presentation Transcript

  • Towards Collaborative Environments for Ontology Construction and Sharing Jie Bao, Doina Caragea and Vasant Honavar Artificial Intelligence Research Laboratory Computer Science Department Iowa State University, Ames, IA USA 50011 Email: {baojie, dcaragea, honavar}@cs.iastate.edu May 15, 2006
  • Outline
    • Motivation
    • Package-based Description Logics: Language Features
    • Package-based Description Logics : Semantics
    • Collaborative Ontology Building Tools
  • Challenges in Ontology Building
    • Collaboration Challenges
      • Integration of local points of view
      • Avoiding inconsistencies and unintended coupling
      • Selective knowledge hiding
      • Partial ontology reuse
    • Scaleability Challenges
      • Editing
      • Storage
      • Reasoning
  • Local vs Global Semantics
    • Ontologies represent local views of its producers
      • Biologist: dog species only eats animal Ontology: Dog is Carnivore and all Carnivore only eats Animal
      • Pet owner: pet dog sometimes eats DogFood, which is not animal Ontology: PetDog is Dog and some Pet Dog eats DogFood ; Dog Food is CannedFood and not Animal
    • Global semantics could lead to conflicts
    • Localizing knowledge is helpful to reduce such risks
  • Partial vs All-or-Nothing Reuse
    • Lack of modularity: all or nothing
      • Eg: how to import part of the animal ontology?
    • Modular ontologies : more flexible partial reuse
      • Less communication
      • Less memory
      • Less parsing time.
      • Less unwanted junk!
    General Pet Poultry Livestock Animal Ontology (Centralized) MyPet General Pet Poultry Livestock MyPet Animal Ontology (Package-extended) Semantic importing Semantics incorporated in MyPet ontology Semantics not presented in MyPet ontology Legend :
  • Organizational vs Semantic Structure
    • Organizational structure: how to arrange terms for better usage and understanding
      • Eg: Computer Science Dictionary and Biology Dictionary
    • Semantic structure: how to relate meanings of terms
      • Eg: ‘Mouse’ is a kind of ‘Animal’ or ‘Mouse’ is part of ‘Computer’
    Animal is a part of
  • Knowledge Hiding vs Sharing
    • Ontology reflects shared knowledge in general
    • However, the provider may also wish to hide part of it.
      • Privacy, Copyright, Security
    • Partial hiding helps for safer ontology organization
      • Reduce unexpected coupling
      • Separate “details” and “interface”
    Locally visible : Has date Globally visible : Has activity Bob’ schedule ontology
  • Ontology Languages Today
    • Description Logics(DL), OWL, OBO (life science ontologies)
    • However, the state of art in ontology languages is reminiscent of the early programming languages
      • Uncontrolled use of global terms
      • Unwanted and uncontrolled interactions between fragments
      • Difficult to reuse: all or nothing
  • Ontology Languages Needed
    • Modularity
      • Has localized terminology and semantics
      • Allows partial ontology reuse
      • Utilizes organizational and semantic structure
      • Enables collaborative and scaleable tools
    • Knowledge Hiding
      • Builds safer ontologies
      • Reduces unwanted interactions
      • Hides details (encapsulate semantics)
  • Outline
    • Motivation
    • Package-based Description Logics: Language Features
    • Package-based Description Logics: Semantics
    • Collaborative Ontology Building Tools
  • P-DL P 3 protected 1. Whole ontology consists of a set of packages 2. Packages are organized in hierarchies 3. Terms and axioms are defined in packages with scope limitations P 1 P 2 public private P 1 P 2 public private
  • Package
    • A package is an ontology module with clearly defined access interface;
    • Each package is defined with certain ontology language and
      • Import: terms from other packages
      • Interface: terms visible to other packages
    • Each term has a home package
    1. Whole ontology consists of a set of packages General Pet Poultry Livestock Animal ontology Hound, Pointer Pet Dog General
  • Nested Package
    • A nested package is part of another package
      • Super package, sub package
      • Form a package hierarchy
    • Could be used to represent the organizational structure
      • Arrange knowledge
      • Enforce hierarchical management of knowledge
    2. Packages are organized in hierarchies General Pet Dog Animal ontology
  • Scope Limitation Modifier
    • Defines the visible scope of a term or axiom
    • SLM of an ontology term or axiom t
      • is a boolean function V(t,r), where r is a package
      • Package r could access t iff V(t,r) = True.
    • Example SLMs
      • Public (t,r): t is accessible from anywhere
      • Private (t,r): t is only available in the home package
      • Protected (t,r): t is accessible from the home package and its recursive sub packages .
    3. Terms has scope limitation P 3 protected P 1 P 2 public private P 1 P 2 public private
  • SLM: example(TBC) A schedule ontology Hidden: details of the activity Visible: there is an activity Hidden semantics may still be used in reasoning
  • Outline
    • Motivation
    • Package-based Description Logics: Language Features
    • Package-based Description Logics : Semantics
    • Collaborative Ontology Building Tools
  • Local Interpretation Ontology: Carnivore Animal Interpretation: In any world that conforms to the ontology, for any instance x of Carnivore, x is also an instance of Animal . Carnivore I P Animal I P Δ I P eats I P goofy I P
  • Local and Global Interpretations Animal I Carnivore I Dog I I PetDog I goofy I Pet I eats I g g g g g g g foo I g DogFood I g Animal I Carnivore I Dog I goofy I foo I Dog I Pet I PetDog I pluto I eats I 1 1 1 1 2 2 2 2 2 2 DogFood I 2 Animal I 2 =
  • Distributed Interpretation
    • Global interpretations may not exist for all packages
    • Distributed interpretations may still exist for selected sets of packages.
    P 1 ,P 2 A B C D 1 B C C P 2 B,C B C 3 B,C = x x’ B I 2 = C I 2 =P I 2 A I 1 = B I 1 ,C I 1 =D I 1 = x x’ B I 3 y A I 1 = B I 1 C I 1 = D I 1 y’ C I 3 P 1 ,P 3
  • Outline
    • Motivation
    • Package-based Description Logics : Language Features
    • Package-based Description Logics : Semantics
    • Collaborative Ontology Building
  • Collaborative Ontology Building
    • Ontology modularity facilitates collaborative building
    • Each package can be independently developed
    • Different curators can concurrently edit the ontology on different packages
    • Ontology can be only partially loaded
    • Unwanted interactions are minimized by limiting term and axiom visibility
    • Module access privileges can be controlled by the package hierarchy
  • The INDUS DAG Editor The COB Editor
  • Summary
    • Collaborative ontology building calls for modular ontology representation.
    • Package-based description logics (P-DL) offers an ontology language for modularity and selective knowledge sharing.
    • Efficient collaborative ontology building tools can be realized with P-DL.
    • Ongoing Work
    • Reasoning algorithm
    • Extension to OWL
    • Backup
  • Ontology Languages Today (2)
    • Distributed Description Logics (DDL)
      • Allows “bridge rules” between concepts across ontology modules
    • E-Connections
      • Connects DL modules with special types of roles called “links”
    • Limitations
      • Expressivity
      • Semantic Soundness
    PetOwner Pet owns Pet Animal Goldfish (onto) (into)
  • Interpretation of Importing
    • Domain relations are compositional consistent : r 13 =r 12 O r 23
      • Therefore domain relations are transitively reusable.
    • Domain relation : individual correspondence between local domains
    • Importing establishes one-to-one domain relations between local domains
      • “ Copied” individuals are shared between local domains
      • Ensure exact reasoning w.r.t. the integrated ontology
    x x’ Δ I 1 Δ I 2 C I 1 C I 2 r 12 Δ I 3 r 13 r 23 x’’ C I 3
  • Animal I Carnivore I Dog I goofy I foo I Dog I Pet I PetDog I pluto I eats I (a) (b) 1 1 1 1 2 2 2 2 2 2 DogFood I 2 Animal I 2 Local Interpretation
    • Semantics of foreign terms is not imported
    • One term may have different local interpretations