Lec#2_SW_Visionx - CSE661SemanticWebSpring2013

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24 Οκτ 2013 (πριν από 4 χρόνια και 17 μέρες)

68 εμφανίσεις

Semantic Web


Quratulain

Rajput

Faculty of Computer Science, IBA

Spring2013

Growth of internet

Quratulain Rajput

2

World Wide Web


Quratulain Rajput

3

World Wide Web


From web 1.0 to web 2.0



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4

Information
access

Information
production

Interactive
participation

Information link with
href


Blog,wiki,social
-
media
-
sites

How big is the web?


Google just released some astounding figures about the size
of the Web. According to a blog post on the Official Google
Blog, the Google index contained 26 million pages in 1998. By
2000, the index reached the one billion mark, and just
recently, Google hit a new milestone: 1 trillion unique
URL’s/links on the web at once
!
[
http://www.emarketingtrends.co.za/2008/07/how
-
big
-
is
-
the
-
web
/]



Google
new Search
Index Caffeine comprises

o
100
Million Gigabytes i.e.
1017 Byte

[http
://
googleblog.blogspot.com/2010/06/our
-
new
-
search
-
index
-
caffeine.html]



Deep web/ Dark web

o
estimated to be about
550 times bigger
than Surface Web
[http://en.wikipedia.org/wiki/Deep_Web]

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5

Semantic data



Data has to enrich semantically, to retrieve relevant
information.


But



What is semantic?

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6

Semantics


Semantics

(from Greek:
sēmantikós
)
is the study of
meaning. It focuses on the relation between
signifiers
, like
words, phrases, signs, and
symbols.


The
semantics of message depends on
syntax
,
context
and
pragmatics and experience.

Quratulain Rajput

7

Syntax


Syntax (From ancient Greek, arrangement
or ordering) is the
study of the principles and
processes by which sentences are
constructed in particular
languages.

o
Formal language syntax:
The
rules governing the behavior
of mathematical
systems (logic).

o
Computer
programming
language syntax:

designed to
communicate instructions to a
computer.


Quratulain Rajput

8

Context


Context(language use) the relevant constraints of
the communicative situation that influence
language
use.


Contexts denotes all elements of any sort of
communication that define
the interpretation
of the
communicated content, as e.g
.,

o
general contexts
: place
, time, interrelation of action in a
message.

o
personal
or social
contexts
: relation
between sender and
receiver of a
message.

Quratulain Rajput

9

Pragmatics


Pragmatics

is a subfield of linguistics which studies
the ways in which context contributes to meaning
.


The study of the speaker's meaning, not focusing on
the phonetic or grammatical form of an
expression,
but instead on what the
speaker's intentions and
beliefs are.

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10

EXPERIENCE


Experience

as a general concept comprises
knowledge of or skill of some thing or some event
gained through involvement in or exposure to that
thing or event

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11


For
successful communication
,


• information has to be correctly transmitted (
Syntax
)


• the meaning (
Semantics
) of the transmitted
information must be


interpreted correctly (=
understanding
)



understanding
depends on


• the
context
of both sender and receiver and


• the
pragmatics
of the sender


• the context of sender and receiver depends on


• the
experience
(knowledge of the world) of both
sender and


receiver

Dr.
Harald

Sack

12

Lack of semantic Problem
in Information retrieval


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13


traditional keyword
-
based
search leads to many not
relevant results


different meanings


polysemy


Contexts missing

Lack of semantic Problem
in Information
Extraction


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14

Lack of semantic Problem
in Information Extraction


Information extraction can only be possible by
a
human.


Information is written in heterogeneous order.


Software
agent
cannot extract information due to
lack of

o
knowledge
of
contexts

o
world
knowledge
and experience

Quratulain Rajput

15

Maintenance problem


Web site is a weakly connected structure of pages.

o
Inconsistency in links (semantically incorrect link or URL changed)


Maintenance is challenging problem to provide
information with correctness and timeliness.

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16

Lack of semantic problem
in Personalization


Adapting user behavior of using/searching
information.


Lack of semantic problem:


user Log file analysis


cookies

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17

Time for Quiz


Define the following terms.

o
Semantic

o
Syntax

o
Context

o
Pragmatic

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18

The vision of the
Semantic
W
eb


The term semantic web proposed by Tim Berners Lee in
the end of 1990’s.


The vision is that machine can participate on the behalf
of user.


Existing search engines using Natural language processing
techniques to extract meaning of information that is then
utilize by machines. But limitation arises when meaning of
information is not possible to extracted. Then the concept
of Semantic Web comes in.



Semantic Web: explicitly annotated information with
semantic metadata. so that information is read and
interpreted correctly by machines.


For example Wikipedia content represent some explicit
metadata, However not using semantic web technology.

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19

I
nformation
representation









How to represent it semantical
l
y.

Quratulain Rajput

20


Dr.
Harald

Sack

21

Dr.
Harald

Sack

22


Well represented
knowledge


The Meaning (Semantics) is expressed with the help
of well
suited knowledge
representations
(Ontologies)

Quratulain Rajput

23

Person

Student

Researcher

subClassOf

subClassOf

Sana

type

hasSuperVisor

domain

range

Saad

type

hasSuperVisor