SEMANTIC WEB

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SEMANTIC WEB
Annarita Giani
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Overview

• Terminology
• Web today
• Semantic Web
• Technologies used
• URI
• RDF
• ONTOLOGIES
• AGENTS
• Future

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Terminology
HTML Hypertext Markup Language XML eXtensible
Markup Language URL Uniform Resource
Locator URI Universal Resource Identifier RDF
Resource Description Framework ONTOLOGIES
Collection of statements written in a language
as RDF that define the relation between concepts
and specify logical rules for reasoning about
them AGENT - Piece of software that runs without
direct human control to accomplish a goal
provided by a user
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Web today
Today Webs content is designed for humans.
Computers programs have difficult to manipulate
it meaningfully
Computers are no reliable way to process the
semantics
If a program read the work cook on a web page
it does not know the meaning.
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Web today cook

• One whose occupation is the preparation of food
  for the table
• Chess. An unforeseen second solution that spoils
  a problem, position
• Intr. To act as cook, to prepare food by the
  action of heat
• Slang phr. to cook with gas (or electricity,
  radar) to succeed, to do very well to act or
  think correctly also to cook on the front (top)
  burner. U.S.
• To play music with excitement, inspiration, slang
  (orig. U.S.).
• trans. To make ready (food) to make fit for
  eating by due application of heat, as by boiling,
  baking, roasting, broiling
• intr. To utter the note of the cuckoo.

10. Cook Island
9. Captain James Cook
8. To disappear suddenly.
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Semantic Web
Semantic Web will bring structure to the
meaningful content of Web pages
It is an extension of the current one.
The Semantic Web allows each information to have
well-defined meaning, enabling computer and
people to work in cooperation.
Data displayed ? Data understood
UNIVERSALITY
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Knowledge representation
Structured information and sets of inference rules

• Centralized
• Decentralized

Challenge provide a language that expresses both
data and rules for reasoning about data
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Technologies

• XML allows users to add arbitrary structure to
  their
• document but says nothing about what the
  structures mean
• Meaning is expressed by RDF which encodes it in
  sets
• of triples ( like subject, verb, object in a
  sentence).
• Object in a RDF are identified by URI
• Ontologies are documents or files that formally
  define
• the relations among terms defined by different
  RDF.
• We also need programs that collect Web content
  from diverse
• sources process the information and exchange the
  results with
• other programs (Agents).

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URI
To identify items on the Web, we also use
identifiers. Because we use a uniform system of
identifiers, and because each item identified is
considered a "resource," we call these
identifiers "Uniform Resource Identifiers" or
URIs We can give a URI to anything, and
anything that has a URI can be said to be "on the
Web.

• I created a Web page for my house.
• I noted on that page that the URL for the page
  serves as the URI for my house.

The URI http//mywepages.com identifies
Annaritas house
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RDF
In RDF a document makes assertions that
particular things have properties with certain
value
This person is sister of another person
This person lives in a city
This person is author of a book
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RDF
Simple RDF statement
ms/reallyLikes Lee/Weaving/ .
The official RDF specification defines an XML
representation of RDF
rdf-syntax-ns" xmlnslove"http//love.example.or
g/terms/" ronsw.com/" rdfresource"http//www.w3.org/People/Berners-Lee
/Weaving/" /
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RDF
The following N-Triples file consists of three
RDF statements
//purl.org/dc/elements/1.1/creator"Dave Beckett"
. ttp//purl.org/dc/elements/1.1/creator"Art
Barstow" . ples/
.
which represents the following RDF/XML
df-syntax-ns" xmlnsdc"http//purl.org/dc/eleme
nts/1.1/" .w3.org/2001/sw/RDFCore/ntriples/"
Art Barstow
Dave Beckett


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RDF
XML / RDF
df-syntax-ns" xmlnsdc"http//purl.org/dc/eleme
nts/1.1/" xmlnsfoaf"http//xmlns.com/0.1/foaf/"


Sean B. Palmer
The Semantic Web An
Introduction

Triples - Notation 3 or N3
_x0
. this
"The Semantic Web An Introduction" . _x0
"Sean B. Palmer"
.
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Ontologies
Two different Database may use different
identifier for the same concept.
Susan
Mary
ZIP CODE 03755
POSTAL CODE 03755
Does Mary and Susan live in the same place??
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Ontologies

• The most typical kind of ontologies for the web
  has
• a taxonomy
• a set of inference rules.

The taxonomy defines classes of objects and
relations among them.
ADDRESS a type of LOCATION, ADDRESS
HAS A ZIP CODE
Inference rules supply more power.
Dartmouth College Address is in Hanover,
NH Hanover, NH is in New Hampshire New Hampshire
is in US
Dartmouth College is in US
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Ontologies
The ontology of cooking and cookbooks includes
the expectation that the products will be eaten
or drunk
ingredients
the difference between simmering and deep-frying
how to stir and combine ingredients
that oil is for cooking in or consuming and not
for lubrication
The Semantic Web "layer cake" as presented by Tim
Berners-Lee
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Ontologies
Not centralized
Recently, a number of research groups have been
developing languages in which to express
ontological expressions on the web
DAML DARPA Agent Markup Language is a language
created by as DARPA as an ontology and inference
langauge based upon RDF, to try to arrive at a de
facto web standard
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Agents
As more machines capable of reading Web content
automatically will become available the
effectiveness of such software agents will
increase
Agents should be skeptical until when they have
checked the source.
Digital signature that proofs that particular
information has been provided by a specific
trusted source.
Value Chain. Information is passed from one agent
to another each one adding value to construct the
final product, what the user were looking for.
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Software agents
Query
Vacation in Florida the second week of August in
a good Hotel close to the beach
Hotel Flight
Mary
The agent looks for meaning to the equest in the
ontologies
The agents interact with the provider to find the
best choice for Mary
PROVIDER
ONTOLOGIES
The agents goes to a provider finder service
and together negotiate using ontologies
PROVIDER FINDER
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A new world
The semantic Web could be extended to the
physical world
Home automation
My microwave will be able to look to the
suggestion that the frozen food producer put on
a web page.
There is already something in this area. Has been
developed a standard for describing functional
capability of devices (e.g. screen size) so that
Web content can be tailored to them on the fly.
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References
www.w3.org www.SemanticWeb.org
www.cs.umd.edu/projects/plus/SHOES/faq.html
http//www.cs.umd.edu/hendler/
http//logicerror.com/semanticWeb-long
http//www.iana.org/assignments/uri-schemes
The Semantic Web Tim Berners-Lee, James
Hendler, Ora lassila
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http//www.cs.umd.edu/hendler/