Semantic Web Technologies: A Tutorial

1
Semantic Web TechnologiesA Tutorial

• Li Ding
• Department of Computer Science
• Rensselaer Polytechnic Institute
• Sept 5, 2007
• Class notes for CSCI-6962 Semantic Web

2
This talk

• This talk covers
• exciting research topics
• pointers to tutorials, portals, news, tools, ...
• examples, experiences, and demos
• This talk is not
• an in-depth tutorial for RDF, RDFS, OWL
• a complete list of semantic web technology
• a user manual for semantic web tools

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The Web has made people smarter
craigslist
Surfing
WWW
Search
bag-of-words
tagging
del.icio.us
4
But what about machines?

• Machines still have a very minimal understanding
  of text and images.

note images borrowed from Tim Finins
presentation
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The Semantic Web and us
Files
Database
action
inference, search, ...
export
Forms
RDF
RDF
RDF
publish

Semantic Web web of data
RDF
publish consume
RDF
RDF
locate translate
talk
HTML
RDF
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The latest semantic web layer cake
source http//www.w3.org/2007/03/layerCake.png
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Selected semantic web topics

• Representation (AI)
• RDF data model
• RDF syntax
• Ontology and additional languages
• Presentation (HCI)
• Editor and Browser
• UI with intelligence behavior
• Computation
• Data Access
• Indexing and Searching the whole Semantic Web
• Very large triple store and SPARQL
• Information integration (aka mashup)
• GRDDL syntax level
• ontology/schema mapping semantic level
• Knowledge discovery
• Inference ontology-based, rule-based, ...
• Network analysis RDF graph, online social
  network

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RDF data model

• Each URI denotes a concept
• URIs are connected by triples
• Machines read data as directed RDF graph

Don't say "colour" say lthttp//example.com/2002/st
d6colgt
RDF (Resource Description Framework)
Relational database
Source Tim Berners-Lee, Putting the Web back
into Semantic Web, ISWC2005 Keynote
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Encoding knowledge in RDF
There is a person whose name is Li Ding.
http//xmlns.com/foaf/0.1/name

• RDF Graph
• URI
• Literal
• Blank-Node
• Triple

Li Ding
t1
http//www.w3.org/1999/02/22-rdf-syntax-nstype
t2
http//xmlns.com/foaf/0.1/Person
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RDF syntax and dialects
http//xmlns.com/foaf/0.1/name
Li Ding
t1
Semantic Wiki
http//www.w3.org/1999/02/22-rdf-syntax-nstype
t2
nameLi Ding
http//xmlns.com/foaf/0.1/Person
lt?xml version"1.0" encoding"utf-8"?gt ltrdfRDF
xmlnsfoaf"http//xmlns.com/foaf/0.1/"
xmlnsrdf"http//www.w3.org/1999/02/22-rdf-syntax
-ns"gt ltrdfDescriptiongt ltrdftype
rdfresource"http//xmlns.com/foaf/0.1/Person"/gt
ltfoafnamegtLi Dinglt/foafnamegt
lt/rdfDescriptiongt lt/rdfRDFgt
ltdiv class"vcard"gt ltdiv class"fn"gtLi
Dinglt/divgt lt/divgt
microformat
ltdl class"foafPerson"gt ltdtgtNamelt/dtgt ltdd
property"foafname"gtLi Dinglt/ddgt
RDFa
RDF/XML
_at_prefix foaf lthttp//xmlns.com/foaf/0.1/gt .
a foafPerson foafname Li Ding" .
N3
_x lthttp//www.w3.org/1999/02/22-rdf-syntax-nsty
pegt lthttp//xmlns.com/foaf/0.1/Persongt. _x
lthttp//xmlns.com/foaf/0.1/namegt Li Ding.
N-Triples
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Ontology spectrum
Thesauri narrower term relation
space of interest
Disjointness, Inverse,part of
Frames (properties)
Formal is-a
Catalog/ID
CYC
RDF
DAML
DB Schema
RDFS
UMLS
Wordnet
OO
IEEE SUO
OWL
General Logical constraints
Formal instance
Value Restriction
Terms/ glossary
Informal is-a
SimpleTaxonomies
ExpressiveOntologies
Source Originally by Deborah L. McGuinness
(KSL, Stanford), modified by Tim Finin
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Stats scale of the Semantic Web
Statistics based Semantic Web data indexed by
Swoogle
Estimated number of documents based on Google
query
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Stats sources of semantic data

• Instance data are mainly from com ( gt39 pure
  SWDs)
• Ontologies are mainly from non-profit
  organizations (gt46 org) and academia (gt14 edu)
• one IP may be shared by many websites (domain
  names) using virtual hosting technology.

note Statistics of top level domain is also used
in characterizing the Web (Henziger and Lawrence
2004)
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Stats usage of semantic web ontologies

• Based on a total of 2,379,164 Semantic Web
  Documents (SWD)
• only a few (about 10) ontologies has been used by
  over 100,000 SWDs
• only 10.4 ontologies has been used by over 10
  SWDs

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Semantic web tools

• Pellet
• Racer Pro
• FACT
• Jena
• JTP
• F-OWL
• Euler
• CWM

Editor
Online Registry

• Protégé
• Swoop

Reasoner

• DAML Ontology Library
• Schema Web

• Jena (SPARQL)
• KAON
• Kowari
• Sesame
• OWLIM
• 3store
• Instance store
• Redland
• Tap
• RDF store
• Yars
• IBM IODT
• RDFLib
• RDF gateway
• allegro
• Oracle 10

create
Search Engine
publish
inference

• Swoogle
• Semantic Web Search

Managing Ontologies
Triple store
instance
browse
Browser

• Tabulator
• IsaViz
• Piggybank
• Arago
• Horus
• Mspace
• Magpie

extend
integrate

• ONION
• PROMPT
• OntoMapper
• Glue
• OntoMerge
• Ontomorph

Mapping Tools
source1 http//ebiquity.umbc.edu/paper/html/id/25
7 source2 http//esw.w3.org/topic/SemanticWebTool
s
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Application OWL for agent communication

• Ontology
• Agents
• Service
• Inference
• Policy

http//cobra.umbc.edu/
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Application semantic content management site
http//ebiquity.umbc.edu/person/html/Li/Ding/

• data stored in database
• PHP generates both HTML and OWL
• HTML pages link to corresponding OWL
• no more web scraping

http//ebiquity.umbc.edu/person/foaf/Li/Ding/foaf.
rdf
FOAF
PHP
PHP
Mysql database
http//ebiquity.umbc.edu/ - ebiquity group
website http//mindswap.org/ - the first site on
the semantic web
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Application semantic web challenges - Winners
2003
2004
Flink itself is also likely to be unique as a
crossover between a social experiment and a
semantic application.
CS AKTive Space (CAS) is an integrated Semantic
Web application which provides a way to explore
the UK Computer Science Research domain across
multiple dimensions for multiple stakeholders,
from funding agencies to individual researchers.
2005
CONFOTO is a browsing and annotation service for
conference photos.
http//challenge.semanticweb.org/
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Challenge manage RDF data versions

• Like Internet Archive RDF graph gt URL gt
  version
• track the evolution of an ontology, e.g., the
  Protege ontology
• track the grows of instance data, e.g., a FOAF
  document.
• Permanent URI for different versions

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Challenge generate RDF data

• Manual
• Text Editor
• Online form
• Ontology Editor
• Semantic Wiki
• (Semi) automated
• GRDDL XHTMLXSL gt RDF/XML
• Information Extraction
• Database/spreadsheet Converter
• Embedded metadata in JPEG, PDF (XMP)

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Summary

• The Semantic Web
• facilitates knowledge sharing and integration
  between human world and machine world
• has many interesting topics semantics, ontology,
  HCI, knowledge management and discovery
• It is growing in real world
• growth of online semantic web data/ontology
• lots of emerging semantic web tools
• more and more semantic web applications
• There are still many challenges