Title: CS690L Semantic Web and Knowledge Discovery: Concept, Technologies, Tool
1CS690LSemantic 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.
2Semantic 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?
3Semantic 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.
4W3C 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
5Resource 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
6RDF Ontology
- Classes
- Resource
- Property
- Literal
- Statement
- Container
- Bag
- Seq
- Alt
- Properties
- type
- subject
- predicate
- object
7RDF 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
8RDF-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.
9Comments 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
10The 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)
11DAMLOIL
- 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
12DAMLOIL Classes
Thing Restriction List Ontology AbstractProperty T
ransitiveProperty DatatypeProperty UniqueProperty
UnambiguousProperty Nothing
13DAMLOIL 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
14Property 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
15Comments 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