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ontology
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Semantic Web and Ontology
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Knowledge and Data Collections
Facilitates Knowledge-to-Knowledge interaction
Web of Knowledge (Semantic Web, Web 3.0)
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Communication between people
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Towards the Semantic Web
• WWW now– Humans do everything– Computers as tools– Problems abound
• WWW in the future– Computers do a lot
more– Computers work on
our behalf– Fewer problems…
How do we get there…?
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The More or Less Global Agreement about Standard Terminology and Conceptual Hierarchy for a Domain
Description is Necessary for the Interoperability in the Intelligent Web
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Motivation: machine-friendly data• Natural Language
• XML – represent structures
• Semantic Web - represent more semantics– represent structures– enable common vocabulary– associate symbols with logic interpretation for
inference
Li Ding is a person
<person>Li Ding</person>
<> </>
as seen by a person
as seen by a person as seen by a machine
as seen by a machine
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Where we are Today: the Syntactic Web
[Hendler & Miller 02]7
i.e. the Syntactic Web is…
• A place where – computers do the presentation (easy) and – people do the linking and interpreting (hard).
• Why not get computers to do more of the hard work?
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Today’s Web• Currently most of the Web content is suitable
for human use.• Typical uses of the Web today are
information seeking, publishing, and searching for people and products, shopping, reviewing catalogues, etc.
• Dynamic pages generated based on information from databases but without original information structure found in databases.
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What is the (Proposed) Solution?
Now... that should clear up a few things around here10
Semantic Web: Motivation & Features
• Current WWW was built for humans, not for machines• Hyperlinks with meaning– agents can navigate the WWW by following semantic
links• What will happen when data comes with semantics?– data from different sources can be combined• new, perhaps unforeseen opportunities and
functionality will result– machines can meaningfully use the WWW and
perform tasks on our behalf (“machine-understandable” content)
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–“An extension of the current Web in which information is given well-defined meaning, better enabling computers and people to work in cooperation.”• Sir Tim Berners-Lee et al., Scientific American, 2001:
tinyurl.com/i59p
–“…allowing the Web to reach its full potential…” with far-reaching consequences–“The next generation of the Web”
What is the Semantic Web?Scientific American Article 2001
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Some Definitions from the W3C“The Semantic Web is the representation of
data on the World Wide Web. It is a collaborative effort led by W3C with participation from a large number of researchers and industrial partners. It is based on the Resource Description Framework (RDF), which integrates a variety of applications using XML for syntax and URIs for naming.”
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Semantic Web Layers
WebAspect
SemanticAspect
HTTP
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The Semantic Web Vision
Semantic Web
Turning the WWW into a machine understandable knowledge base
Ontologies
KnowledgeMarkup
IntelligentAgents
Applications
Documents
Databases15
What is an Ontology?A model of (some aspect of) the world• Introduces vocabulary
relevant to domain, e.g.:– Anatomy– Cellular biology– Aerospace– Dogs– Hotdogs– …
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What is an Ontology?
A model of (some aspect of) the world• Introduces vocabulary
relevant to domain• Specifies meaning (semantics)
of termsHeart is a muscular organ thatis part of the circulatory system
• Formalised using suitable logic
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Studer(98): Formal, explicit specification of a shared conceptualization
Machine readable
Concepts, properties,functions, axiomsare explicitly defined
Consensualknowledge
Abstract model of some phenomenain the world
What is an ontology?
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Ontologies – Example
OntologyF-Logic
similar
city
NeckarZugspitze
Geographical Entity (GE)
Natural GE Inhabited GE
countryrivermountain
instance_of
Germany
BerlinStuttgart
is-a
flow_through
located_in
capital_of
flow_through
flow_through
located_in
capital_of
367
length (km)
2962
height (m)
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SW: Use casesBooking a flightInteraction between office computer, flight company, travel agency, shuttle services, hotel, my calendar
Finding a restaurantInteraction between mobile device, map service, recommendation service, restaurant reservation service
Web searchCombining information from different sources to figure out whether to hire Innova
Intelligent homeFridge knows my calendar, orders food if I am planning a dinner
Intelligent cars Car knows my schedule, where and when to get gas, how not to hit other cars, what are the legal regulations
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Role of Semantic Web• Semantic Web representation mechanisms -
ideally suited to – describing people and the objects that link them
together– recording and representing the heterogeneous ties
involved. • Semantic Web -useful platform for – performing operations on diverse, distributed person-
and object-related data. • Object-centered networks and user-centric
services for generating collaborative content can serve as rich data sources for Semantic Web applications.
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Semantic Web vs. Web 2.0 (Ora Lassila)Semantic Web vs. Web 2.0 (Ora Lassila)
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