Transcript Semantic Web - Perceptual Intelligence Laboratory

By
Ahmet Can Babaoğlu
Abdurrahman Beşinci
Suppose you want to buy a Star wars DVD having such
properties;
 wide-screen ( not full-screen )
 the extra disc of bonus materials
 lowest available price
 not paying too much for shipping and handling
 not waiting too long for delivery.
What would you do?
 The best thing you can do is to search for web pages and
look for a suitable item.
 However, using semantic web, agents can return the suitable
results to you…
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An agent lists the prices of flat screen HDTVs
with properties;
 larger than 40 inches with 1080p resolution
 at shops in the nearest town
 open until 8pm on Tuesday evenings
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Find and buy a airline ticket if there is a route
from Istanbul to London
this evening with price lower than $150
Tim Berners-Lee (1998 )
Inventor of WWW, URIs, HTTP, and HTML
 The director of the World Wide Web
Consortium ( www.w3.org )
 Senior researcher at the MIT Computer
Science and Artificial Intelligence Laboratory
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A Web that includes
 documents, or portions of documents,
 describing explicit relationships between things and
 containing semantic information intended for
 automated processing by our machines.
TBL’s words;
Now web is a huge book, with semantic web, it will be a huge
database.
A technology helps machines `understand`;
◦ The Beatles was a popular band from Liverpool.
◦ John Lennon was a member of the Beatles.
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Machine process-able
Data integration
Meaningful web pages
Making deductions
SW is not AI and AI is not SW
SW should be a great playground for AI
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Web of data - provides common data
representation framework to facilitate
integrating multiple sources to draw new
conclusions
Increase the utility of information by
connecting it to its definitions and to its
context
More efficient information access and
analysis
Agents searching Web and retrieving valuable
information to the end user.
 Web services publishing their information
 Programs running to merge data of different
web services and create new results from
them.
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User:
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Machine:
Exciting world - semantics of the resource, understood
from content
Very little information available , only links
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User: Even more exciting world, richer user experience
Machine: More processable information is available (Data Web)
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Metadata layer ( Resource and property )
RDF ( Resource Description Framework )
Schema layer
( Hierarchical description of concepts )
RDF-S ( RDF Schema )
Logical layer ( class relations, uses logic )
OWL ( Web Ontology Language )
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1.
2.
XML:
RDF:
uses tags to describe data
provides a framework to describe resources.
uses triples written as XML tags to express this information
as a graph.
Q:
There is a father relation between Anakin and Luke ok but,
who or what is Anakin and Luke ? What does father mean
anyway?
A:
RDF uses uniform resource identifiers (URIs) to direct the
computer to a document or object that represents the
resource.
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Computers don't have the kind of vocabulary that
people do. So the computer has to have documents that
describe all the words and logic to make the necessary
connections.
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RDF-S:
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OWL:
adds classes, subclasses and properties to
resources, creating a basic language framework
formalizes ontology, describes relationships between
classes and uses logic to make deductions. It can also
construct new classes based on existing information.
<http://aaronsw.com/>
<http://love.example.org/terms/reallyLikes> <http://www.w3.org/People/BernersLee/Weaving/> .
Explanation;
The first URI is the subject. the subject is me.
The second URI is the predicate. It is "reallyLikes."
The third URI is the object. The object is Tim Berners-Lee's book "Weaving the Web." So the
RDF statement above says that I really like "Weaving the Web.“
RDF code;
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:love="http://love.example.org/terms/" >
<rdf:Description rdf:about="http://aaronsw.com/">
<love:reallyLikes rdf:resource="http://www.w3.org/People/Berners-Lee/Weaving/" />
</rdf:Description>
</rdf:RDF>
To declare a vocabulary or properties
 specify the (multiple)-inheritance links between the types of
classes (subClassOf or subProperty);
 machines determine
the meanings of resources
based on properties and
classes.
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<rdf:RDF xml:base="http://www.inria.fr/2007/04/17/humans.rdfs" xmlns:rdf
="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xmlns="http://www.w3.org/2000/01/rdf-schema#">
<Class rdf:ID="Man">
<subClassOf rdf:resource="#Person"/>
<subClassOf rdf:resource="#Male"/>
<label xml:lang="en">man</label>
<comment xml:lang="en">an adult male person</comment> </Class>
<rdf:Property rdf:ID="hasMother">
<subPropertyOf rdf:resource="#hasParent"/>
<range rdf:resource="#Female"/> <domain rdf:resource="#Human"/>
<label xml:lang="en">has for mother</label>
<comment xml:lang="en">to have for parent a female.</comment>
</rdf:Property> </rdf:RDF>
We declare a class #Man, sub class of #Person and #Male, and a property #hasMother
having sub property of #hasParent, and that is used between instances of the class
#Human and instances of the class #Female.
making logical deductions. For instance, given the ontology above, a
Semantic Web agent could infer that since "Goose" is a type of
"DarkMeatFowl," and "DarkMeatFowl" is a subset of the class "Fowl,"
which is a subset of the class "EdibleThing," then "Goose" is an
"EdibleThing."
<owl:SymmetricProperty rdf:ID="sibling">
<rdfs:domain rdf:resource="#Animal" />
<rdfs:range rdf:resource="#Animal" />
</owl:SymmetricProperty>
A property is symmetric.
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Precise search results
Time efficient for human
Easy to publish information
More human like thinking ( one step closer )
Data integration
Machine process-able
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The learning curve. RDF was developed by people with
academic background in logic and artificial intelligence. For
traditional developers it is not very easy to understand.
All the web pages’ content must be changed which is a long
process.
Unrealized idea; "This simple idea, however, remains largely
unrealized."
Two formats for one piece of data: one for human viewing
and one for machines
concerns regarding censorship and privacy (for governments
to control the viewing and creation of online information )
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Semantic Web infrastructure - stimulate the
network effect of data
Data Access
Best Practices for vocabulary / ontology
development
Development of ontology registries for Open
vocabularies