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The Semantic Web: An Introduction | PDF
INTRODUCTION TO
THE SEMANTIC WEB
Elena Simperl, University of
Southampton, UK
e.simperl@soton.ac.uk
@esimperl
THE BEGINNINGS
“The Semantic Web is not a separate
Web but an extension of the current
one, in which information is given well-
defined meaning, better enabling
computers and people to work in
cooperation”
[Berners-Lee, Hendler & Lassila, 2001]
NOT A SEPARATE WEB
Decentralized information space (for people)
Consisting of documents and other Web resources
 Uniquely identified
 Connected to each other via hyperlinks
 Accessed via the Internet
 Created and used by different parties
Technologies
 URIs
 HTML
 HTTP
http://info.cern.ch/hypertext/WWW/TheProject.html
BUT AN EXTENSION OF THE CURRENT ONE
A decentralized information space (for computers and people)
A Web of data
Consisting of information and non-information resources
 Uniquely identified
 Connected to each other via hyperlinks
 Accessed via the Internet
 Created and used by different parties
INFORMATION WITH WELL-DEFINED MEANING
Machines can process Web
information ‘intelligently
One can encode this additional
information in a machine-
processable way
Using formal knowledge
representation languages and
reasoning
This article is about a person
This article is about a writer
People and writers have
characteristic properties e.g.,
• they are born somewhere
• they publish books
• books have topics, chapters, a
price etc.
COMPUTERS AND PEOPLE WORK IN
COOPERATION
Artificial intelligence: “the science and engineering of making intelligent
machines”
[John Mc Carthy, http://www-formal.stanford.edu/jmc/whatisai/whatisai.html]
Areas of AI
 Knowledge representation
 Inference
 Logics
 Search
 Planning and scheduling
 Pattern recognition
 Learning
 Natural language processing
 Computer vision
 Robotics
 ....
MEANING ON THE WEB
 Add metadata to Web resources
 Different types of links
 Encode additional information about metadata entities and links in
ontologies
 No global information schemas
 Incomplete and inconsistent
[Examples from Wikipedia]
YOU DON’T HAVE TO BUILD YOUR OWN ONTOLOGY
LINKED DATA MAKES DATA INTEGRATION EASY
Concepts, entities, and properties are
accessible on the Web just as traditional Web
documents
Linked Data: Set of technologies and
principles to publish and access data on the
Web
http://lod-cloud.net/
http://www.ted.com/talks/tim_berners_lee_o
n_the_next_web.html
SEMANTIC WEB STACK
Standardized family of languages
 Compatible with the Web architecture
 With a formal semantics
Linked data is part of the stack
Tools
 Editors
 Data stores
 Reasoners
 Machine learning
 NLP
 Data interlinking
 …
FROM THE SEMANTIC WEB TO SEMANTIC
TECHNOLOGIES
“The Semantic Web provides a
common framework that allows data to
be shared and reused across
application, enterprise, and community
boundaries”
[W3C]
EXAMPLE: KNOWLEDGE GRAPH
MAKING SEARCH MORE INTELLIGENT
http://googleblog.blogspot.gr/2012/05/introducing-knowledge-graph-things-not.html
EXAMPLE: BBC & MEDIA
CONTENT PUBLISHING AND INTEGRATION
EXAMPLE: OPEN GRAPH
INTEROPERABLE CONTENT REPRESENTATION
Represent Web content in a social graph in
an interoperable way
Used by Facebook (‘stories’), Google
(snippets), IMDb etc.
Facebook: actors, apps, objects with
metadata to create stories
 Example: Elena has finished reading ‘The
Economist’, an object of type Newspaper
 Types with attributes, extensions allowed
 Pre-defined and custom actions on objects
14
http://ogp.me/
Image from
https://developers.facebook.com/docs/opengraph/creatin
g-custom-stories
29-Aug-15
EXAMPLE: PROJECT HALO
29.08.2015
Images from http://www.projecthalo.com and http://www.inquireproject.com/
EXAMPLE: DATA.GOV
USING LINKED DATA TO PUBLISH GOVERNMENT OPEN DATA
SEMANTIC WEB TODAY
Semantic Web technologies, standardized by the W3C,
are mature
 RDF recommendation in 1999, update in 2004
 RDFa (RDF in HTML) note in 2008
 RDFS recommendation in 2004
 SPARQL recommendation in 2008
 OWL recommendation in 2004, update in 2009
Schema.org markup (RDFa, microformats, microdata)
 http://www.webdatacommons.org/structureddata/
Linked Open Data
 http://linkeddatacatalog.dws.informatik.uni-
mannheim.de/state/
Ontologies
 http://lov.okfn.org/dataset/lov/
JOIN THE SEMANTIC WEB COMMUNITY
Mailing lists
 public_lod
 semanticweb
 Diverse others for special topics (Dbpedia,
schema.org etc.)
Facebook, LinkedIn, Quora
Conferences
 Academic: ESWC, ISWC, WWW, AAAI etc.
 Applied/industry: Semantics, SmartData etc.
Workshops
 Knowledge Discovery and Data Mining Meets
Linked Open Data @ESWC
 Consuming Linked Data @ISWC
 Detection, Representation, and Exploitation of
Events in the Semantic Web @ESWC
 Services and Applications over Linked APIs and
Data @ESWC
 Ontology Alignment Evaluation Initiative
@ISWC
 Semantic Statistics @ISWC
 Ontology Design Patterns @ISWC
 NLP & Dbpedia @ISWC
 Linked Data for Information Extraction @ISWC
 …

The Semantic Web: An Introduction

  • 1.
    INTRODUCTION TO THE SEMANTICWEB Elena Simperl, University of Southampton, UK e.simperl@soton.ac.uk @esimperl
  • 2.
    THE BEGINNINGS “The SemanticWeb is not a separate Web but an extension of the current one, in which information is given well- defined meaning, better enabling computers and people to work in cooperation” [Berners-Lee, Hendler & Lassila, 2001]
  • 3.
    NOT A SEPARATEWEB Decentralized information space (for people) Consisting of documents and other Web resources  Uniquely identified  Connected to each other via hyperlinks  Accessed via the Internet  Created and used by different parties Technologies  URIs  HTML  HTTP http://info.cern.ch/hypertext/WWW/TheProject.html
  • 4.
    BUT AN EXTENSIONOF THE CURRENT ONE A decentralized information space (for computers and people) A Web of data Consisting of information and non-information resources  Uniquely identified  Connected to each other via hyperlinks  Accessed via the Internet  Created and used by different parties
  • 5.
    INFORMATION WITH WELL-DEFINEDMEANING Machines can process Web information ‘intelligently One can encode this additional information in a machine- processable way Using formal knowledge representation languages and reasoning This article is about a person This article is about a writer People and writers have characteristic properties e.g., • they are born somewhere • they publish books • books have topics, chapters, a price etc.
  • 6.
    COMPUTERS AND PEOPLEWORK IN COOPERATION Artificial intelligence: “the science and engineering of making intelligent machines” [John Mc Carthy, http://www-formal.stanford.edu/jmc/whatisai/whatisai.html] Areas of AI  Knowledge representation  Inference  Logics  Search  Planning and scheduling  Pattern recognition  Learning  Natural language processing  Computer vision  Robotics  ....
  • 7.
    MEANING ON THEWEB  Add metadata to Web resources  Different types of links  Encode additional information about metadata entities and links in ontologies  No global information schemas  Incomplete and inconsistent [Examples from Wikipedia]
  • 8.
    YOU DON’T HAVETO BUILD YOUR OWN ONTOLOGY
  • 9.
    LINKED DATA MAKESDATA INTEGRATION EASY Concepts, entities, and properties are accessible on the Web just as traditional Web documents Linked Data: Set of technologies and principles to publish and access data on the Web http://lod-cloud.net/ http://www.ted.com/talks/tim_berners_lee_o n_the_next_web.html
  • 10.
    SEMANTIC WEB STACK Standardizedfamily of languages  Compatible with the Web architecture  With a formal semantics Linked data is part of the stack Tools  Editors  Data stores  Reasoners  Machine learning  NLP  Data interlinking  …
  • 11.
    FROM THE SEMANTICWEB TO SEMANTIC TECHNOLOGIES “The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries” [W3C]
  • 12.
    EXAMPLE: KNOWLEDGE GRAPH MAKINGSEARCH MORE INTELLIGENT http://googleblog.blogspot.gr/2012/05/introducing-knowledge-graph-things-not.html
  • 13.
    EXAMPLE: BBC &MEDIA CONTENT PUBLISHING AND INTEGRATION
  • 14.
    EXAMPLE: OPEN GRAPH INTEROPERABLECONTENT REPRESENTATION Represent Web content in a social graph in an interoperable way Used by Facebook (‘stories’), Google (snippets), IMDb etc. Facebook: actors, apps, objects with metadata to create stories  Example: Elena has finished reading ‘The Economist’, an object of type Newspaper  Types with attributes, extensions allowed  Pre-defined and custom actions on objects 14 http://ogp.me/ Image from https://developers.facebook.com/docs/opengraph/creatin g-custom-stories 29-Aug-15
  • 15.
    EXAMPLE: PROJECT HALO 29.08.2015 Imagesfrom http://www.projecthalo.com and http://www.inquireproject.com/
  • 16.
    EXAMPLE: DATA.GOV USING LINKEDDATA TO PUBLISH GOVERNMENT OPEN DATA
  • 17.
    SEMANTIC WEB TODAY SemanticWeb technologies, standardized by the W3C, are mature  RDF recommendation in 1999, update in 2004  RDFa (RDF in HTML) note in 2008  RDFS recommendation in 2004  SPARQL recommendation in 2008  OWL recommendation in 2004, update in 2009 Schema.org markup (RDFa, microformats, microdata)  http://www.webdatacommons.org/structureddata/ Linked Open Data  http://linkeddatacatalog.dws.informatik.uni- mannheim.de/state/ Ontologies  http://lov.okfn.org/dataset/lov/
  • 18.
    JOIN THE SEMANTICWEB COMMUNITY Mailing lists  public_lod  semanticweb  Diverse others for special topics (Dbpedia, schema.org etc.) Facebook, LinkedIn, Quora Conferences  Academic: ESWC, ISWC, WWW, AAAI etc.  Applied/industry: Semantics, SmartData etc. Workshops  Knowledge Discovery and Data Mining Meets Linked Open Data @ESWC  Consuming Linked Data @ISWC  Detection, Representation, and Exploitation of Events in the Semantic Web @ESWC  Services and Applications over Linked APIs and Data @ESWC  Ontology Alignment Evaluation Initiative @ISWC  Semantic Statistics @ISWC  Ontology Design Patterns @ISWC  NLP & Dbpedia @ISWC  Linked Data for Information Extraction @ISWC  …