Download - L18 My SemWeb
-
8/3/2019 L18 My SemWeb
1/46
241-320 Design Architecture and Engineeringfor Intelligent System
Suntorn Witosurapot
Contact Address: Phone : 074 287369 or
Email: [email protected]
January 2011
-
8/3/2019 L18 My SemWeb
2/46
Lecture 18:
Introduction to Semantic Web
-
8/3/2019 L18 My SemWeb
3/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 3
Preview:
In the last chapter, we have learned varioustechniques of Machine Learning , which make thecomputer (or agent) becomes intelligence.
We remain study the same issue in this lecture,, butshift the domain to the Web , which becomes anessential to our daily life.
We will learn how the web content can turn to be a
knowledge base so that it can be searched or queriedin the intellgent manner.
-
8/3/2019 L18 My SemWeb
4/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 4
Outline
Semantic Web BasicsSemantic Web Applications
Semantic Web Services Basics
-
8/3/2019 L18 My SemWeb
5/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 5
Semantic Web
The Semantic Web is an extension of thecurrent web in which information is given well-defined meaning , better enabling computers and
people to work in co-operation .[Berners-Lee et al., 2001]
-
8/3/2019 L18 My SemWeb
6/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 6
Semantic Web Vision
-
8/3/2019 L18 My SemWeb
7/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 7
Todays Web: the Syntactic Web
-
8/3/2019 L18 My SemWeb
8/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 8
The Syntactic Web is
A hypermedia, a digital library A library of documents called (web pages)
interconnected by a hypermedia of links
A database, an application platform A common portal to applications accessiblethrough web pages, and presenting their resultsas web pages
A platform for multimedia BBC Radio 4 anywhere in the world!A naming scheme Unique identity for those documents
-
8/3/2019 L18 My SemWeb
9/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 9
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?
-
8/3/2019 L18 My SemWeb
10/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 11
Hard Work using the Syntactic Web
Complex queries involving background knowledge Find information about animals that use sonar but
are not either bats, dolphins or whales
Locating information in data repositories Travel enquiries Prices of goods and services Results of human genome experiments
Delegating complex tasks to web agents Book me a holiday next weekend somewhere warm,
not too far away, and where they speak French orEnglish
-
8/3/2019 L18 My SemWeb
11/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 12
What is the Problem?
Consider a typical web page:Markup consists of: rendering
information (e.g.,font size andcolour)
Hyper-links torelated content
Semantic content is
accessible tohumans but not(easily) tocomputers
-
8/3/2019 L18 My SemWeb
12/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 13
What information can we see
WWW2002The eleventh international world wide web conferenceSheraton waikiki hotel, Honolulu, hawaii, USA7-11 may 2002, 1 location 5 days learn interactRegistered participants coming fromaustralia, canada, chile denmark, france, germany, ghana, hong kong,,
norway, singapore, switzerland, the united kingdom, the unitedstates, vietnam, zaire
Register nowOn the 7 th May Honolulu will provide the backdrop of the eleventh
international world wide web conference. This prestigious event..
Speakers confirmedTim berners-leeTim is the well known inventor of the Web, Ian FosterIan is the pioneer of the Grid, the next generation internet
-
8/3/2019 L18 My SemWeb
13/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 14
What information can a machine see
-
8/3/2019 L18 My SemWeb
14/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 15
XML User definable and domain specific markup
Knowledge Management
Manager: John Davies Project: SEKT
HTML:
Knowledge Management John Davies SEKT
XML:
-
8/3/2019 L18 My SemWeb
15/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web 16
XML: Document = labelled tree
course
teachertitle students
name http
... ...
......
...
=
DTD: simple grammars to describe legal trees
node = label + contents
-
8/3/2019 L18 My SemWeb
16/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
17
Solution: XML markup with meaningful tags?
-
8/3/2019 L18 My SemWeb
17/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
18
But What About
CV
name
education
work
private
< >
< >
-
8/3/2019 L18 My SemWeb
18/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
19
Only feasible for closed collaboration agents in a small & stable community pages on a small & stable intranet
.. not for sharable Web-resources
XML: limitations for semantic markup
XML makes no commitment on: Domain specific ontological vocabulary
Which words shall we use to describe a given set of concepts? Ontological modelling primitives
How can we combine these concepts, e.g. car is a-kind-of(subclass-of) vehicle
requires pre-arranged agreement on vocab & primitives
-
8/3/2019 L18 My SemWeb
19/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
20
Limitations of the Web today
Machine-to-human, not machine-to-machine
-
8/3/2019 L18 My SemWeb
20/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
21
Limitations of the Web today (cont.)
You can easily search for documents (e.g. via GoogleSearch Engine), but can not extract information
-
8/3/2019 L18 My SemWeb
21/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
22
Limitations of the Web today (cont.)
You can easily search for documents (e.g. via GoogleSearch Engine), but can not extract information
-
8/3/2019 L18 My SemWeb
22/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
23
What should the web be served for?Combining information
-
8/3/2019 L18 My SemWeb
23/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
24
What should the web be served for?Combining information (cont.)
-
8/3/2019 L18 My SemWeb
24/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
25
How can we make the web to do that?
Instead of publishing natural language, publishmachine-processable data !
Publish information in terms understandable for amachine
Ask questions in terms understandable for a machine
And: make sure all machines understand your terms!
-
8/3/2019 L18 My SemWeb
25/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
26
XML is a first step
Semantic markup HTML layout XML meaning
Metadata within documents, not across documents Prescriptive ( ) , not descriptive (
)
No commitment on vocabulary and modellingprimitives
RDF is the next step
-
8/3/2019 L18 My SemWeb
26/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
27
Detour: Flat File Records
Consider the following records in flat file:
011500 18.66 0 0 62 46.271020111 25.220010011500 26.93 0 1 63 68.951521001 32.651010020100 33.95 1 0 65 92.532041101 18.930110020100 17.38 0 0 67 50.351111100 42.160001
What do they mean?
-
8/3/2019 L18 My SemWeb
27/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
28
Detour: Metadata
NAME LENGTH FORMAT LABELinstudy 6 MMDDYY Date of randomization
into studybmi 8 Num Body Mass Index.obesity 3 0=No 1=Yes Obesity (30.0
-
8/3/2019 L18 My SemWeb
28/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
29
Detour: Schema
A flat file is a collection of records.
A record consists of fields.
Each record in a flat file has the same number andkinds of fields as any other record in the same file.
The schema of a flat file describes the structure(i.e., the kinds of fields) of each record.
-
8/3/2019 L18 My SemWeb
29/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
30
Detour: Self-Describing Data
Schema
-
8/3/2019 L18 My SemWeb
30/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
31
RDF is beyond XML
RDF is a language for representing information aboutresources in the web.
While RDF is expressed in XML, it has differentsemantics.
Resource Description Framework
XML RDF
Element Type Class
Element Instance Resource
Data attribute DatatypeProperty
Reference attribute ObjectProperty
Containment Property
XML vs. RDFTerminology
-
8/3/2019 L18 My SemWeb
31/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
32
RDF for semantic annotation
RDF provides metadata about Web resourcesObject -> Attribute-> Value triplesIt has an XML syntaxChained triples form a graph
http://www.aifb.uni-karlsruhe.de/WBS/ysu
site-owner
York 608659
2
telW3C
explains
http://www.w3.org/RDF
site-owner
< rdf:Description rdf:about =#York>< tel >6086592
-
8/3/2019 L18 My SemWeb
32/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
33
What does RDF Schema add?
Defines vocabulary for RDF Organizes this vocabulary in a
typed hierarchy Class, subClassOf, type Property, subPropertyOf domain, range
Rudi York
Person
PhDStud Professor
subClassOf subClassOf
type
hasSuperVisordomain range
typehasSuperVisor
RDFS
RDF
-
8/3/2019 L18 My SemWeb
33/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
34
-
8/3/2019 L18 My SemWeb
34/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
35
Conclusions about RDF(S)
Next step up from plain XML: (small) ontological commitment to modeling
primitives
possible to define vocabulary
However: no precisely described meaning
no inference model
-
8/3/2019 L18 My SemWeb
35/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
36
The semantic pyramid again
-
8/3/2019 L18 My SemWeb
36/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
37
The Ontology layer
ontology = shared conceptualization=> conceptual model
(more expressive than RDF + RDFS)
=> expressed in a true knowledge representationlanguage
OWL (Web Ontology Language) = standardlanguage for ontologies
-
8/3/2019 L18 My SemWeb
37/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
38
Ontology
Ontologies enable a better communication
between Humans/MachinesOntologies standardize and formalize the meaningof words through concepts
An ontology is an explicit specification of a conceptualization .
People cant share knowledge if they do not speak a common language .
-
8/3/2019 L18 My SemWeb
38/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
39
^
Communication Principle
ReferentFormStands for
refers toevokes
Concept
Jaguar
-
8/3/2019 L18 My SemWeb
39/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
40
Views on Ontologies
Front-End
Back-End
TopicMaps
Extended ER-Models
Thesauri
Predicate Logic
Semantic Networks
Taxonomies
Ontologies
Navigation
Queries
Sharing of Know ledge
I nformation Retrieval
Query Expansion
Mediation Reasoning
Consistency CheckingEA I
-
8/3/2019 L18 My SemWeb
40/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
41
Taxonomy
Object
Person Topic Document
ResearcherStudent Semantics
OntologyDoctoral Student
Taxonomy := Segementation, classification and ordering of elementsinto a classification system according to their relationships betweeneach other
PhD Student F-Logic
Menu
-
8/3/2019 L18 My SemWeb
41/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
42
Thesaurus
Object
Person Topic Document
ResearcherStudent Semantics
PhD StudentDoctoral Student
Terminology for specific domain Graph with primitives, 2 fixed relationships (similar, synonym) originate from bibliography
similarsynonym
OntologyF-Logic
Menu
-
8/3/2019 L18 My SemWeb
42/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
43
Topic Map
Object
Person Topic Document
ResearcherStudent Semantics
PhD StudentDoctoral Student
knows described_in
writes
AffiliationTel
Topics (nodes), relationships and o ccurences (to documents) ISO-Standard typically for navigation- and visualisation
OntologyF-Logic
similarsynonym
-
8/3/2019 L18 My SemWeb
43/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
44
OntologyF-Logic
similar
OntologyF-Logic
similar
PhD StudentDoktoral Student
Ontology (in our sense)
Object
Person Topic Document
Tel
PhD StudentPhD Student
Semantics
knows described_in
writes
Affiliationdescribed_in is_about
knowsP writes D is_about T P T
DT T D
Rules
subTopicOf
Representation Language: Predicate Logic (F-Logic) Standards: RDF(S); coming up standard: OWL
ResearcherStudent
instance_of
is_a
is_a
is_aAffiliation
Affiliation
York Sure
AIFB+49 721 608 6592
-
8/3/2019 L18 My SemWeb
44/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
45
PhD Student AssProf
AcademicStaff
rdfs:subClassOfrdfs:subClassOf
cooperate_with
rdfs:rangerdfs:domainOntology
Steffen Staab
...
http://www.aifb.uni-karlsruhe.de/WBS/sst
Anno-tation
Siegfried
Handschuh
...
WebPage
http://www.aifb.uni-karlsruhe.de/WBS/shaURL
instance of
instanceof
Cooperate_with
Ontology & Metadata
Links have explicit meanings!
-
8/3/2019 L18 My SemWeb
45/46
241-320 Design Architecture &Engineering for Intelligent System Introduction to Semantic Web
46
Summary
The emergence of the Semantic Web
machine-processable information
Language stack: XML/RDF(S)/OWL Ontologies
-
8/3/2019 L18 My SemWeb
46/46
Introduction to Semantic Web
Checking your understanding
What are the semantic web layers?What is the key difference between thesemantic and syntactic web?