Transcript Computer communication B

Computer
communication B
Introduction to the Semantic Web
The semantic web: definitions

What is the semantic web?
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Nobody knows exactly, because there are broad and varying
definitions about it.
Tim-Berners Lee, the inventor of the WWW says (Berners-Lee,
Hendlers, J. & Lassila, O., 2001)
“Most of the Web's content today is designed for humans to
read, not for computer programs to manipulate meaningfully.
Computers can adeptly parse Web pages for layout and routine
processing here a header, there a link to another page but in
general, computers have no reliable way to process the
semantics…. The Semantic Web will bring structure to the
meaningful content of Web pages, creating an environment
where software agents roaming from page to page can readily
carry out sophisticated tasks for users.
The semantic web: definitions

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, Hendlers, J. & Lassila, O.,
2001)
The semantic web (SW): definitions
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“The Semantic Web is a vision: the idea of
having data on the Web defined and linked in a
way that it can be used by machines not just for
display purposes, but for automation, integration
and reuse of data across various applications
(W3C, 2003)
“Soon it will be possible to access the Web
resources by content rather than just by
keywords (Anutariya et al, 2001)
Semantic Web: Introduction
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The content of the present Word Wide Web is
nowadays only accessible and can be
elaborated only by people
The Semantic Web is an enlargement of the
WWW with semantic information that can be
used by computers
With the help of semantic information the
content of pages could be processed
automatically and computers could make
inferences about a search
Semantic Web: Software-agents

Software-agents: are part of software that act in
place of the user or in place of another program
in relation to an agency (for example the so
called “collaborative filtering”)
 They
simulate the qualities and the properties and/or
the preferences of their users
 They search for extra information on the basis of
which additional decision can be taken
 They take action independently, and they can
communicate with the user
 Example: By purchasing something the softwareagent proposes something that is related to it
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With the Semantic Web software-agents
could execute complicated assignments
for which they need relevant information
 Organization
meetings or plan trips
 Select specific suppliers to buy a product
The semantic web: characteristics
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The semantic web is not different from the www,
is actually a developing part of it.
The infrastructures and characteristics should be
common
 Use
 Use
URI (Uniform resource Identifiers) addressing
protocols that a have a small and universally
understood set of commands (like HTTP: Hypertext
Transfer Protocol)
 Be decentralized (like the www)
 Function on a large scale
The semantic web: The layer cake
The semantic web
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Two principles for the construction of the semantic web
1.
Downward compatibility. Agents fully aware of a layer should also
be able to interpret and use information written at lower levels. For
example, agents aware of the semantics of OWL can take full
advantage of information written in RDF and RDF Schema.
2.
Upward partial understanding. On the other hand, agents fully
aware of a layer should take at least partial advantage of
information at higher levels. For example, an agent aware only of
the RDF and RDF Schema semantics can interpret knowledge
written in OWL partly, by disregarding those elements that go
beyond RDF and RDF Schema.
Bibliography
The Semantic Web, Scientific American,
May 2001, Tim Berners-Lee, James
Hendler and Ora Lassila.
 http://www.w3.org/
 Antoniou, G., Van Harmelen, F. `(2004) “A
Semantic web Primer”
http://www.netlibrary.com/Reader/
