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CS690L Semantic Web and Knowledge Discovery: Concept, Technologies, Tool

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Language for describing the structure of document content e.g., declare data to ... rdf:Class ID='MiniVan' rdfs:subClassOf rdf:resource='#Van' ... – PowerPoint PPT presentation

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Title: CS690L Semantic Web and Knowledge Discovery: Concept, Technologies, Tool


1
CS690LSemantic Web and Knowledge Discovery
Concept, Technologies, Tool
  • Yugi Lee
  • STB 555
  • (816) 235-5932
  • leeyu_at_umkc.edu
  • www.sice.umkc.edu/leeyu
  • This presentation was designed based on
  • Richard Fikess tutorial on Ontologies and
    Semantic Web.

2
Semantic Web Language
  • XML
  • Language for describing the structure of document
    content e.g., declare data to be a retail price,
    a sales tax, a book title, ...
  • Uniform method for describing and exchanging data
    using HTTP
  • Provides a syntactic schema
  • ltPublication URL "ftp//db.stanford xml.psgt
  • ltTitlegt From Semistructured Data ... Language
    lt/Titlegt
  • ltAuthorgt R. Goldman lt/Authorgt
  • ltPublishedgt Proceedings of ... Databases
    lt/Publishedgt
  • ltLocationgt Location of
    what?
  • ltCitygt Philadelphia lt/Citygt
  • ltStategt Pennsylvania lt/Stategt
  • lt/Locationgt
  • ltDategt
  • ltMonthgt June lt/Monthgt
  • ltYeargt 1999 lt/Yeargt
  • lt/Dategt
  • lt/Publicationgt

When in June?
3
Semantic Web Language
  • XML Is Not Enough
  • Ontologies enable independently developed
    programs to exchange data XML provides
    syntactic schema
  • Ontologies specify intended meaning in a computer
    interpretable form XML provides no means of
    specifying intended meaning of tags
  • XML is like HTML, where you make up your own
    tags.
  • But in XML, you cant say what your tags mean.

4
W3C Semantic Web Activity
  • Semantic Web Activity (http//www.w3.org/2001/sw/)
  • Established to serve a leadership role, in both
    the design of enabling specifications and the
    open, collaborative development of technologies
    that support the automation, integration and
    reuse of data across various applications.
  • Successor to the W3C Metadata Activity
  • RDF Core Working Group (http//www.w3.org/2001/sw/
    RDFCore/)
  • Responsible for the Resource Description
    Framework (RDF)
  • Web Ontology Working Group (http//www.w3.org/2001
    /sw/WebOnt/)
  • Charter Build upon the RDF Core work a language
    for defining structured web based ontologies
    which will provide richer integration and
    interoperability of data among descriptive
    communities
  • Developing Ontology Web Language (OWL) Based on
    DAMLOIL, developed in DARPAs Agent Markup
    Language program

5
Resource Description Framework (RDF)
  • A simple representation language for describing
    Web resources
  • All sentences are triples of the form (Property
    Subject Object)
  • Property is a binary relation
  • Subject is a URI reference
  • Object is either a URI reference or a literal
  • E.g., (creatorOf http//www.w3.org/Lassila Ora
    Lassila)
  • XML external syntax, Model theoretic semantics
  • Includes a resource Class and properties
    type, subclassOf, etc.
  • Supports classes of resources and literals (type
    Elephant Clyde)
  • Supports subclass hierarchies (subclassOf
    Elephant Mammal)
  • Like a primitive frame representation language

6
RDF Ontology
  • Classes
  • Resource
  • Property
  • Literal
  • Statement
  • Container
  • Bag
  • Seq
  • Alt
  • Properties
  • type
  • subject
  • predicate
  • object

7
RDF Schema
  • An ontology added to RDF
  • Classes
  • Class
  • ContainerMembershipProperty
  • Properties
  • subClassOf
  • subPropertyOf
  • seeAlso
  • isDefinedBy
  • comment
  • label
  • range
  • domain
  • member

Resource
Literal
Class
Property
Container
Statement
ContainerMembershipProperty
Bag
Seq
Alt
8
RDF-S Class and Property Definitions
ltrdfClass ID"MotorVehicle"gt
ltrdfssubClassOf rdfresource"http.../PR-rdf-sche
ma-19990303Resource"/gt lt/rdfClassgt ltrdfClass
ID"PassengerVehicle"gt ltrdfssubClassOf
rdfresource"MotorVehicle"/gt lt/rdfClassgt ltrdfC
lass ID"Van"gt ltrdfssubClassOf
rdfresource"MotorVehicle"/gt lt/rdfClassgt ltrdfC
lass ID"MiniVan"gt ltrdfssubClassOf
rdfresource"Van"/gt ltrdfssubClassOf
rdfresource"PassengerVehicle"/gt
lt/rdfClassgt ltrdfProperty ID "registeredTo"gt
ltrdfsdomain rdfresource MotorVehicle /gt
ltrdfsrange rdfresource Person
/gt lt/rdfPropertygt
Christine is a passenger vehicle. Is Christine a
motor vehicle? Yes.
Christine is registered to Arnie. What is
Arnie? A person.
9
Comments on RDF and RDF-S
  • Severely lacking in expressive power
  • Domain and range constraints rather than
    Value-Type
  • E.g., cant define class of people all of whose
    children are male
  • No cardinality constraints
  • Particularly important for exactly 1 and at
    most 1
  • No decompositions
  • Particularly important for disjoint and
    exhaustive
  • No axioms
  • No negation (!)
  • Not useful for checking consistency
  • E.g., cant prove an object is not an instance of
    a class
  • Basically a typing system

10
The DAML Program
  • DAML DARPA Agent Markup Language
  • Defense Advanced Research Agency (DARPA) program
  • Program Managers James Hendler, Murray Burke
  • Begin in August 2000
  • Goal achieve semantic interoperability between
    Web pages, databases, programs, and sensors
  • Integration contractor and 16 technology
    development teams
  • MIT (Tim Berners-Lee, Ben Grosof)
  • Stanford (Gio Weiderhold, Richard Fikes, Deborah
    McGuinness)
  • UMBC (Tim Finin)
  • U West Florida (Pay Hayes)
  • Yale (Drew McDermott)
  • Web site http//www.daml.org/
  • Cycorp (Doug Lenat)
  • Nokia (Ora Lassila)
  • Teknowledge (Bob Balzer)

11
DAMLOIL
  • A representation language for user-defined
    ontologies
  • An ontology added to RDF and RDF-Schema
  • Specification document
  • http//www.daml.org/2000/12/damloil-index.html
  • Expressive power analogous to
  • Description logics (e.g., CLASSIC)
  • Monotonic frame languages (e.g., OKBC knowledge
    model)
  • Designed in collaboration with the European
    Community
  • Designers of the Ontology Inference Layer (OIL)
  • Basis for OWL, the candidate W3C standard

12
DAMLOIL Classes
Thing Restriction List Ontology AbstractProperty T
ransitiveProperty DatatypeProperty UniqueProperty
UnambiguousProperty Nothing
13
DAMLOIL Properties
  • Classes
  • disjointWith
  • Defining Non-primitive classes
  • unionOf, disjointUnionOf, intersectionOf,
    complementOf, oneOf
  • Restrictions
  • onProperty, toClass, hasValue, hasClass,
    hasClassQ
  • minCardinality, maxCardinality, cardinality
  • minCardinalityQ, maxCardinalityQ, cardinalityQ
  • Equivalence
  • equivalentTo, sameClassAs, samePropertyAs
  • Lists
  • first, rest, item
  • Properties
  • inverseOf
  • Ontologies
  • versionInfo, imports

14
Property Restrictions on Classes
ltClass ID "Person"gt ltcommentgt Person is a
subclass of objects whose parents are persons.
lt/commentgt ltrdfssubClassOfgt
ltdamlRestrictiongt ltdamlonProperty
rdfresource hasParent /gt
ltdamltoClass rdfresource Person /gt
lt/damlRestrictiongt lt/rdfssubClassOfgt ltcomment
gt Person is a subclass of resources that have
one father. lt/commentgt ltrdfssubClassOfgt
ltdamlRestrictiongt ltdamlonProperty
rdfresource hasFather /gt
ltdamlcardinalitygt 1 lt/damlcardinalitygt
lt/damlRestrictiongt lt/rdfssubClassOfgt
15
Comments on DAMLOIL and OWL
  • Expressive power of a description logic
  • Representation language for both classes and
    instances
  • Additional expressive power needed (at least FOL)
  • No rationale for excluding any axiom from an
    ontology that is
  • Not a tautology
  • Satisfied by the intended interpretation of the
    ontology
  • Example of need for additional expressive power
  • The magnitude of a physical quantity in a given
    unit of measure
  • (gt (AND (Quantity-Magnitude ?q ?u ?m)
    (Quantity-Dimension ?q ?d))
  • (AND (type Physical-Quantity ?q) (type
    Unit-Of-Measure ?u)
  • (type Magnitude ?m)
    (Unit-Dimension ?u ?d)))
  • May be too difficult for the Web community to
    understand
  • Acceptance will be depend on user-friendly tools
  • Ok to support development of Semantic Web
    technology
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