Semantic WebSemantic Web
Presented by:Presented by:
Edward ChengEdward Cheng
Wayne ChoiWayne Choi
Tony DengTony Deng
Peter Kuc-PittetPeter Kuc-Pittet
Anita YongAnita Yong
AgendaAgenda
IntroductionIntroduction Semantic Web componentsSemantic Web components ExampleExample Pros/ConsPros/Cons
The Current World Wide The Current World Wide WebWeb
Network of hypertext documents Network of hypertext documents containing text, images, audio, and videocontaining text, images, audio, and video
Is readable and understandable by Is readable and understandable by humans, but only readable (via parsing) by humans, but only readable (via parsing) by machinesmachines
What is missing is this understanding of What is missing is this understanding of the semanticsthe semantics
For exampleFor example vs.
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SemanticsSemantics The definition of semantics is meaningThe definition of semantics is meaning The idea is to give a keyword (or a subject) a The idea is to give a keyword (or a subject) a
definitiondefinition These definitions are then related to objects These definitions are then related to objects Humans do this easily but often make mistakes, Humans do this easily but often make mistakes,
so to have computers perform these operations so to have computers perform these operations would eliminate mistakeswould eliminate mistakes
Does not mean that there are no mistakes in the Does not mean that there are no mistakes in the algorithms used, but idea is that using the logic of algorithms used, but idea is that using the logic of Semantic Web these errors could be caughtSemantic Web these errors could be caught
What is Semantic Web?What is Semantic Web? Tim Berners-Lee’s vision of a network of data fully Tim Berners-Lee’s vision of a network of data fully
understandable by machines without requiring understandable by machines without requiring human interventionhuman intervention
Standardized way of defining relations between Standardized way of defining relations between things that have meaningthings that have meaning
A globally and semantically linked network of A globally and semantically linked network of information underlying the current Webinformation underlying the current Web
ComponentsComponents
Unicode:Unicode: A standard and universal way of encoding A standard and universal way of encoding
texttext
URI URI (Uniform Resource Identifier)(Uniform Resource Identifier):: A unique string identifying a name or A unique string identifying a name or
resourceresource
XML XML (Extensible Markup Language)(Extensible Markup Language):: Used to describe and communicate dataUsed to describe and communicate data
ComponentsComponents
Namespaces:Namespaces: A way of encapsulating a vocabularyA way of encapsulating a vocabulary
XML Query:XML Query: Used to extract data from an XML Used to extract data from an XML
documentdocument
XML Schema:XML Schema: A description of an XML document, A description of an XML document,
imposing constraints on its content and imposing constraints on its content and structurestructure
ComponentsComponents
RDF Model RDF Model (Resource Description (Resource Description
Framework)Framework):: Makes a statement about a resource Makes a statement about a resource
using a (subject, predicate, object) URI using a (subject, predicate, object) URI tripletriple ((http://santa.comhttp://santa.com, ,
http://xmlns.com/foaf/0.1/#term_interest, http://xmlns.com/foaf/0.1/#term_interest, http://en.wikipedia.org/wiki/Dietinghttp://en.wikipedia.org/wiki/Dieting
Santa is interested in Wikipedia’s dieting entrySanta is interested in Wikipedia’s dieting entry
OntologyOntology An ontology is a data model that describes individuals, An ontology is a data model that describes individuals,
classes, attributes, and relationsclasses, attributes, and relations
RDF schema is the base RDF ontology, putting RDF schema is the base RDF ontology, putting constraints on an RDF subject’s relationship to an object constraints on an RDF subject’s relationship to an object for a given predicatefor a given predicate foaf:person foaf:knows foaf:personfoaf:person foaf:knows foaf:person foaf:image foaf:knows foaf:personfoaf:image foaf:knows foaf:person
OWL (Web Ontology Language):OWL (Web Ontology Language): A more complicated and expressive ontology than RDF SchemaA more complicated and expressive ontology than RDF Schema Three forms: OWL Lite, OWL DL, OWL FullThree forms: OWL Lite, OWL DL, OWL Full
QueryingQuerying
A Semantic Web query connects to A Semantic Web query connects to multiple RDF dataset agents to gather multiple RDF dataset agents to gather information, and returns the set of best information, and returns the set of best matched results.matched results.
Cheapest Support Labour?
North AmericanFirm A
North AmericanFirm B
OverseasFirm A
Agent Agent Agent
Bob: Book doctors appointment
Target: Person
Type: Patient
Type: Bob
Type: Doctor
Type: Rick
Target: Hospital
Employee
Target: Schedule
Time
Type: Sched Type: Sched
Time Time Time
ProsPros
Searching with semantic meaning and Searching with semantic meaning and relationsrelations
Agents (programs) acting as Agents (programs) acting as intermediaries to meet user needs intermediaries to meet user needs
Better knowledge management as data is Better knowledge management as data is connected in meaningful waysconnected in meaningful ways
ConsCons
Need to maintain two different versions of Need to maintain two different versions of web content – a machine readable version web content – a machine readable version and a human interaction versionand a human interaction version
Only useful if Semantic Web is adopted by Only useful if Semantic Web is adopted by the massesthe masses