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

    1. 1. 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
    2. 2. Outline <ul><li>Motivation </li></ul><ul><li>Package-based Description Logics: Language Features </li></ul><ul><li>Package-based Description Logics : Semantics </li></ul><ul><li>Collaborative Ontology Building Tools </li></ul>
    3. 3. Challenges in Ontology Building <ul><li>Collaboration Challenges </li></ul><ul><ul><li>Integration of local points of view </li></ul></ul><ul><ul><li>Avoiding inconsistencies and unintended coupling </li></ul></ul><ul><ul><li>Selective knowledge hiding </li></ul></ul><ul><ul><li>Partial ontology reuse </li></ul></ul><ul><li>Scaleability Challenges </li></ul><ul><ul><li>Editing </li></ul></ul><ul><ul><li>Storage </li></ul></ul><ul><ul><li>Reasoning </li></ul></ul>
    4. 4. Local vs Global Semantics <ul><li>Ontologies represent local views of its producers </li></ul><ul><ul><li>Biologist: dog species only eats animal Ontology: Dog is Carnivore and all Carnivore only eats Animal </li></ul></ul><ul><ul><li>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 </li></ul></ul><ul><li>Global semantics could lead to conflicts </li></ul><ul><li>Localizing knowledge is helpful to reduce such risks </li></ul>
    5. 5. Partial vs All-or-Nothing Reuse <ul><li>Lack of modularity: all or nothing </li></ul><ul><ul><li>Eg: how to import part of the animal ontology? </li></ul></ul><ul><li>Modular ontologies : more flexible partial reuse </li></ul><ul><ul><li>Less communication </li></ul></ul><ul><ul><li>Less memory </li></ul></ul><ul><ul><li>Less parsing time. </li></ul></ul><ul><ul><li>Less unwanted junk! </li></ul></ul>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 :
    6. 6. Organizational vs Semantic Structure <ul><li>Organizational structure: how to arrange terms for better usage and understanding </li></ul><ul><ul><li>Eg: Computer Science Dictionary and Biology Dictionary </li></ul></ul><ul><li>Semantic structure: how to relate meanings of terms </li></ul><ul><ul><li>Eg: ‘Mouse’ is a kind of ‘Animal’ or ‘Mouse’ is part of ‘Computer’ </li></ul></ul>Animal is a part of
    7. 7. Knowledge Hiding vs Sharing <ul><li>Ontology reflects shared knowledge in general </li></ul><ul><li>However, the provider may also wish to hide part of it. </li></ul><ul><ul><li>Privacy, Copyright, Security </li></ul></ul><ul><li>Partial hiding helps for safer ontology organization </li></ul><ul><ul><li>Reduce unexpected coupling </li></ul></ul><ul><ul><li>Separate “details” and “interface” </li></ul></ul>Locally visible : Has date Globally visible : Has activity Bob’ schedule ontology
    8. 8. Ontology Languages Today <ul><li>Description Logics(DL), OWL, OBO (life science ontologies) </li></ul><ul><li>However, the state of art in ontology languages is reminiscent of the early programming languages </li></ul><ul><ul><li>Uncontrolled use of global terms </li></ul></ul><ul><ul><li>Unwanted and uncontrolled interactions between fragments </li></ul></ul><ul><ul><li>Difficult to reuse: all or nothing </li></ul></ul>
    9. 9. Ontology Languages Needed <ul><li>Modularity </li></ul><ul><ul><li>Has localized terminology and semantics </li></ul></ul><ul><ul><li>Allows partial ontology reuse </li></ul></ul><ul><ul><li>Utilizes organizational and semantic structure </li></ul></ul><ul><ul><li>Enables collaborative and scaleable tools </li></ul></ul><ul><li>Knowledge Hiding </li></ul><ul><ul><li>Builds safer ontologies </li></ul></ul><ul><ul><li>Reduces unwanted interactions </li></ul></ul><ul><ul><li>Hides details (encapsulate semantics) </li></ul></ul>
    10. 10. Outline <ul><li>Motivation </li></ul><ul><li>Package-based Description Logics: Language Features </li></ul><ul><li>Package-based Description Logics: Semantics </li></ul><ul><li>Collaborative Ontology Building Tools </li></ul>
    11. 11. 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
    12. 12. Package <ul><li>A package is an ontology module with clearly defined access interface; </li></ul><ul><li>Each package is defined with certain ontology language and </li></ul><ul><ul><li>Import: terms from other packages </li></ul></ul><ul><ul><li>Interface: terms visible to other packages </li></ul></ul><ul><li>Each term has a home package </li></ul>1. Whole ontology consists of a set of packages General Pet Poultry Livestock Animal ontology Hound, Pointer Pet Dog General
    13. 13. Nested Package <ul><li>A nested package is part of another package </li></ul><ul><ul><li>Super package, sub package </li></ul></ul><ul><ul><li>Form a package hierarchy </li></ul></ul><ul><li>Could be used to represent the organizational structure </li></ul><ul><ul><li>Arrange knowledge </li></ul></ul><ul><ul><li>Enforce hierarchical management of knowledge </li></ul></ul>2. Packages are organized in hierarchies General Pet Dog Animal ontology
    14. 14. Scope Limitation Modifier <ul><li>Defines the visible scope of a term or axiom </li></ul><ul><li>SLM of an ontology term or axiom t </li></ul><ul><ul><li>is a boolean function V(t,r), where r is a package </li></ul></ul><ul><ul><li>Package r could access t iff V(t,r) = True. </li></ul></ul><ul><li>Example SLMs </li></ul><ul><ul><li>Public (t,r): t is accessible from anywhere </li></ul></ul><ul><ul><li>Private (t,r): t is only available in the home package </li></ul></ul><ul><ul><li>Protected (t,r): t is accessible from the home package and its recursive sub packages . </li></ul></ul>3. Terms has scope limitation P 3 protected P 1 P 2 public private P 1 P 2 public private
    15. 15. SLM: example(TBC) A schedule ontology Hidden: details of the activity Visible: there is an activity Hidden semantics may still be used in reasoning
    16. 16. Outline <ul><li>Motivation </li></ul><ul><li>Package-based Description Logics: Language Features </li></ul><ul><li>Package-based Description Logics : Semantics </li></ul><ul><li>Collaborative Ontology Building Tools </li></ul>
    17. 17. 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
    18. 18. 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 =
    19. 19. Distributed Interpretation <ul><li>Global interpretations may not exist for all packages </li></ul><ul><li>Distributed interpretations may still exist for selected sets of packages. </li></ul>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
    20. 20. Outline <ul><li>Motivation </li></ul><ul><li>Package-based Description Logics : Language Features </li></ul><ul><li>Package-based Description Logics : Semantics </li></ul><ul><li>Collaborative Ontology Building </li></ul>
    21. 21. Collaborative Ontology Building <ul><li>Ontology modularity facilitates collaborative building </li></ul><ul><li>Each package can be independently developed </li></ul><ul><li>Different curators can concurrently edit the ontology on different packages </li></ul><ul><li>Ontology can be only partially loaded </li></ul><ul><li>Unwanted interactions are minimized by limiting term and axiom visibility </li></ul><ul><li>Module access privileges can be controlled by the package hierarchy </li></ul>
    22. 22. The INDUS DAG Editor The COB Editor
    23. 23. Summary <ul><li>Collaborative ontology building calls for modular ontology representation. </li></ul><ul><li>Package-based description logics (P-DL) offers an ontology language for modularity and selective knowledge sharing. </li></ul><ul><li>Efficient collaborative ontology building tools can be realized with P-DL. </li></ul><ul><li>Ongoing Work </li></ul><ul><li>Reasoning algorithm </li></ul><ul><li>Extension to OWL </li></ul>
    24. 24. <ul><li>Backup </li></ul>
    25. 25. Ontology Languages Today (2) <ul><li>Distributed Description Logics (DDL) </li></ul><ul><ul><li>Allows “bridge rules” between concepts across ontology modules </li></ul></ul><ul><li>E-Connections </li></ul><ul><ul><li>Connects DL modules with special types of roles called “links” </li></ul></ul><ul><li>Limitations </li></ul><ul><ul><li>Expressivity </li></ul></ul><ul><ul><li>Semantic Soundness </li></ul></ul>PetOwner Pet owns Pet Animal Goldfish (onto) (into)
    26. 26. Interpretation of Importing <ul><li>Domain relations are compositional consistent : r 13 =r 12 O r 23 </li></ul><ul><ul><li>Therefore domain relations are transitively reusable. </li></ul></ul><ul><li>Domain relation : individual correspondence between local domains </li></ul><ul><li>Importing establishes one-to-one domain relations between local domains </li></ul><ul><ul><li>“ Copied” individuals are shared between local domains </li></ul></ul><ul><ul><li>Ensure exact reasoning w.r.t. the integrated ontology </li></ul></ul>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
    27. 27. 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 <ul><li>Semantics of foreign terms is not imported </li></ul><ul><li>One term may have different local interpretations </li></ul>

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