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

Wedding CakeWedding Cake

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

Questions?Questions?