Jarrar.lecture notes.aai.2011s.ontology part1_introduction

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  • 1. Lecture Notes
    University of Birzeit
    2nd Semester, 2010
    Advanced Artificial Intelligence (SCOM7341)
    Ontology
    Part 1Introduction
    Dr. Mustafa Jarrar
    mjarrar@birzeit.eduwww.jarrar.info
    University of Birzeit
  • 2. Reading Material
    0) Everything in these slides
    1)Thomas R. Gruber: Toward Principles for the Design of Ontologies Used for Knowledge Sharing http://tomgruber.org/writing/onto-design.pdf
    2)Nicola Guarino: Formal Ontology and Information Systems
    http://www.loa-cnr.it/Papers/FOIS98.pdf
  • 3. Shared meaning (i.e. formal semantics) of bibliographical Terminology
    Ontology-based Applications
    (i) Data Integration and Semantic Mediation
    Semantic Mediator
    Product ⊑ ValuatedBy.Price
    Book ⊑ Product ⊓ hasISBN
    ⊓ hasTitle
    ⊓ hasAuthor
    Bookstore Ontology
  • 4. Shared meaning (i.e. formal semantics) of bibliographical Terminology
    Ontology-based Applications
    (i) Data Integration and Semantic Mediation
    Semantic Mediator
    ….
    <owl:Class rdf:ID="Product" />
    <owl:Class rdf:ID="Book">
    <rdfs:subClassOf rdf:resource="#Product" />
    </owl:Class>
    <owl:Class rdf:ID="Price" />
    <owl:Class rdf:ID="Value" />
    <owl:Class rdf:ID="Currency" />
    <owl:Class rdf:ID="Title" />
    <owl:Class rdf:ID="ISBN" />
    <owl:Class rdf:ID="Author" />
    <owl:ObjectProperty rdf:ID="Valuated-By">
    <rdfs:domain rdf:resource="#Product" />
    <rdfs:range rdf:resource="#Price" />
    </owl:ObjectProperty>
    <owl:DataProperty rdf:ID=" Amounted-To .Value">
    <rdfs:domain rdf:resource="#Price" />
    <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
    </owl:ObjectProperty>
    <owl:DataProperty rdf:ID="Measured-In.Currency">
    <rdfs:domain rdf:resource="#Price" />
    <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>

    Bookstore Ontology
    Specification using
    OWL
    (Ontology Web Langauge
  • 5. Ontology-based Applications
    (ii)The Semantic Web scenario
  • 6.
    “The semantic web” mission:
    syntax to semantic based search,  The next generation of the web.
    Ontology
    Buy mobile-phone from Ramallah
    Ontology-based Applications
    (ii)The Semantic Web scenario
    Represents the meanings of thing, in a way that Google can understand. The meaning is embedded inside web pages.
    1
    2
    3
    4
    .
    .
    .
    3 billion pages
  • 7. Ontology-based Applications
    (iii) Web Information Systems
    Information System
    Conceptual Schema
    DBMS
    Apps
    Logical Schema
    Query processor
    Data
    • Each Information System is made for one organization.
    • 8. Why do we need conceptual schemes? for designing Information systems at the conceptual level.
  • Ontologies/ Semantics
    (OWL)
    IS1
    ISn
    Conceptual Schema
    Conceptual Schema
    Agreed data schemes
    (XML, RDF)
    DBMS
    DBMS
    Logical Schema
    Logical Schema
    Apps
    Apps
    Query processor
    Query processor
    Data
    Data
    Ontology-based Applications
    (iii) Web Information Systems
    New needs:
    Open data exchange, inter-organizational transactions, global queries…
  • 9. Example (Customer Complaint Ontology)
    Central complaining portal
    See http://www.jarrar.info/publications/mjarrar-CCFORM-chapter.pdf.htm
  • 10. Example (Customer Complaint Ontology)
    See http://www.jarrar.info/publications/mjarrar-CCFORM-chapter.pdf.htm
  • 11. The Need for a Shared Understanding
    [Martin Hepp]
    People, organizations, and computers needs to communicate meaningfully.
    However, due to different needs and background contexts, there can be widely varying viewpoints and assumptions regarding what is essentially the same subject matter; each may have differing, overlapping and or mis-matched concepts.
    The consequent lack of a shared understanding leads to poor communication within and between people, organizations, and systems.
  • 12. The meaning of Meaning
    Concept
    “Jaguar“
    البَغْوَر
    • Humans require words (or at least symbols) to communicate efficiently. The mapping of words to things is indirect. We do it by creating concepts that refer to things.
    • 13. The relation between symbols and things has been described in the form of the meaning triangle:
    Ogden, C. K. & Richards, I. A. 1923. "The Meaning of Meaning." 8th Ed. New York, Harcourt, Brace & World, Inc
    [Carole Goble, Nigel Shadbolt, Ontologies and the Grid Tutorial]
  • 14. The meaning of Meaning
    Concept
    “Jaguar“
    البَغْوَر
    Concept: a set of rules we have in mind
    to distinguish similar things in reality.
    An instance of a concept
    (الماصدق)
  • 15. The puzzle of Meaning
    • A Term (/symbol) may refer to different concepts (Animal: Jaguar, Car:Jaguar)
    • 16. A Concept might not be agreed among all people (i.e., not exactly the same set of rules are agreed by all people)
    • 17. An instance may belong to different concepts (Person: Mustafa, Lecturer: Mustafa).
    Dictionaries represent meanings approximately and informally, mixed with lexical aspects.
    Ontologies specify the meaning formally and precisely.
  • 18. Levels of Ontological Precision
    [Guarino]
    game(x) -> activity(x)
    athletic game(x) -> game(x)
    court game(x) ↔ athletic game(x) ∧ ∃y. played_in(x,y) ∧ court(y)
    tennis(x) -> court game(x)
    double fault(x) -> fault(x) ∧ ∃y. part_of(x,y) ∧ tennis(y)
    game
    NT athletic game
    NT court game
    RT court
    NT tennis
    RT double fault
    Axiomatized Theories
    Catalog
    game
    athletic game
    court game
    tennis
    outdoor game
    field game
    football
    Glossary
    Thesaurus
    tennis
    football
    game
    field game
    court game
    athletic game
    outdoor game
    Taxonomy
    OO/DB schema
    Ontological Precision
  • 19. Standard Vocabularies are not the Solution
    Contract: A binding agreement between two or more legal persons that is enforceable by law; an
    invoice can be a contract.
    Complaint: An expression of grievance or resentment issued by a complainant against a compliant-recipient,
    describing a problem(s) that needs to be resolved.
    Legal Person:An entity with legal recognition in accordance with law. It has the legal capacity to represent
    its own interests in its own name, before a court of law, to obtain rights or obligations for ….
    • Defining standard vocabularies is difficult and time-consuming
    • Once defined, standards don’t adapt well
    • Heterogeneous domains need a broad-coverage vocabulary
    • People don’t implement standards correctly anyway
    • Vocabulary definitions are often ambiguous or circular
  • 20. A Common Alphabet is not Enough…
    <Book>
    <Title>Orientalism</Title>
    <Author>Edward Said</Author>
    <Price>11</Price>
    </Book>
    <aaa>
    <bbb>Orientalism</bbb>
    <ccc>Edward Said</ccc>
    <ddd>11</ddd>
    </aaa>
    “XML is only the first step to ensuring that computers can communicate freely. XML is an alphabet for computers and as everyone who travels in Europe knows, knowing the alphabet doesn’t mean you can speak Italian or French”
    Business Week, March 18, 2002
  • 21. The Need for Meaning Mediation
    “Lack of technologies and products to dynamically mediate discrepancies in business semantics will limit the adoption of advanced Web services for large public communities whose participants have disparate business processes”
    Gartner Research, February 28, 2002
  • 22. Human and Machine Communication
    [Maedche et al., 2002]
    • ...
    Machine
    Agent 1
    Human
    Agent 2
    Machine
    Agent 2
    Human
    Agent 1
    exchange symbol,
    e.g. via nat. language
    exchange symbol,
    e.g. via protocols
    Ontology Description
    Symbol
    ‘‘JAGUAR“
    Formal Semantics
    Formal
    models
    Internal
    models
    commit
    commit
    Concept
    Meaning
    Triangle
    MA1
    MA2
    HA2
    HA1
    commit
    Ontology
    commit
    a specific
    domain, e.g.
    animals
    Things