1. Ontology

2. History of the Semantic Web
Web was “invented” by Tim Berners-Lee (amongst others), a physicist working at CERN
TBL’s original vision of the Web was much more ambitious than the reality of the existing (syntactic) Web:
TBL (and others) have since been working towards realising this vision, which has become known as the Semantic Web
E.g., article in May 2001 issue of Scientific American…
“... a goal of the Web was that, if the interaction between person and hypertext could be so intuitive that the machine-readable information space gave an accurate representation of the state of people's thoughts, interactions, and work patterns, then machine analysis could become a very powerful management tool, seeing patterns in our work and facilitating our working together through the typical problems which beset the management of large organizations.”

3. Realising the complete “vision” is too hard for now (probably)
Scientific American, May 2001:
Realising the complete “vision” is too hard for now (probably)
But we can make a start by adding semantic annotation to web resources

4. Where we are Today: the Syntactic Web

5. 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 accessible through web pages, and presenting their results as web pages
A platform for multimedia
BBC Radio 4 anywhere in the world! Terminator 3 trailers!
A naming scheme
Unique identity for those documents
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?

6. Impossible (?) using the Syntactic Web…
Complex queries involving background knowledge
Find information about “animals that use sonar but are not either bats or dolphins”
Locating information in data repositories
Travel enquiries
Prices of goods and services
Results of human genome experiments
Finding and using “web services”
Visualize surface interactions between two proteins
Delegating complex tasks to web “agents”
Book me a holiday next weekend somewhere warm, not too far away, and where they speak French or English

7. What is the Problem? Consider a typical web page:
Markup consists of:
rendering information (e.g., font size and colour)
Hyper-links to related content
Semantic content is accessible to humans but not (easily) to computers…

8. What information can we see…
WWW2002
The eleventh international world wide web conference
Sheraton waikiki hotel
Honolulu, hawaii, USA
7-11 may 2002
1 location 5 days learn interact
Registered participants coming from
australia, canada, chile denmark, france, germany, ghana, hong kong, india, ireland, italy, japan, malta, new zealand, the netherlands, norway, singapore, switzerland, the united kingdom, the united states, vietnam, zaire
Register now
On the 7th May Honolulu will provide the backdrop of the eleventh international world wide web conference. This prestigious event …
Speakers confirmed
Tim berners-lee
Tim is the well known inventor of the Web, …
Ian Foster
Ian is the pioneer of the Grid, the next generation internet …

9. What information can a machine see…
WWW2002
The eleventh international world wide web conference
Sheraton waikiki hotel
Honolulu, hawaii, USA
7-11 may 2002
1 location 5 days learn interact
Registered participants coming from
australia, canada, chile denmark, france, germany, ghana, hong kong, india, ireland, italy, japan, malta, new zealand, the netherlands, norway, singapore, switzerland, the united kingdom, the united states, vietnam, zaire
Register now
On the 7th May Honolulu will provide the backdrop of the eleventh international world wide web conference. This prestigious event …
Speakers confirmed
Tim berners-lee
Tim is the well known inventor of the Web, …
Ian Foster
Ian is the pioneer of the Grid, the next generation internet …

10. Solution: XML markup with “meaningful” tags?
<name>WWW2002
The eleventh international world wide webcon</name>
<location>Sheraton waikiki hotel
Honolulu, hawaii, USA</location>
<date>7-11 may 2002</date>
<slogan>1 location 5 days learn interact</slogan>
<participants>Registered participants coming from
australia, canada, chile denmark, france, germany, ghana, hong kong, india, ireland, italy, japan, malta, new zealand, the netherlands, norway, singapore, switzerland, the united kingdom, the united states, vietnam, zaire</participants>
<introduction>Register now
On the 7th May Honolulu will provide the backdrop of the eleventh international world wide web conference. This prestigious event …
Speakers confirmed</introduction>
<speaker>Tim berners-lee</speaker>
<bio>Tim is the well known inventor of the Web,</bio>…

11. Machine sees… <name>WWW2002
The eleventh international world wide webc</name>
<location>Sheraton waikiki hotel
Honolulu, hawaii, USA</location>
<date>7-11 may 2002</date>
<slogan>1 location 5 days learn interact</slogan>
<participants>Registered participants coming from
australia, canada, chile denmark, france, germany, ghana, hong kong, india, ireland, italy, japan, malta, new zealand, the netherlands, norway, singapore, switzerland, the united kingdom, the united states, vietnam, zaire</participants>
<introduction>Register now
On the 7th May Honolulu will provide the backdrop of the eleventh international world wide web conference. This prestigious event …
Speakers confirmed</introduction>
<speaker>Tim berners-lee</speaker>
<bio>Tim is the well known inventor of the W</bio>
<speaker>Ian Foster</speaker>
<bio>Ian is the pioneer of the Grid, the ne</bio>

12. Need to Add “Semantics”
External agreement on meaning of annotations
E.g., Dublin Core
Agree on the meaning of a set of annotation tags
Problems with this approach
Inflexible
Limited number of things can be expressed
Use Ontologies to specify meaning of annotations
Ontologies provide a vocabulary of terms
New terms can be formed by combining existing ones
Meaning (semantics) of such terms is formally specified
Can also specify relationships between terms in multiple ontologies

13. Ontology: Origins and History
a philosophical discipline—a branch of philosophy that
deals with the nature and the organisation of reality
Science of Being (Aristotle, Metaphysics, IV, 1)
Tries to answer the questions:
What characterizes being?
Eventually, what is being?
Ontology in Philosophy

14. Ontology in Linguistics
Referent
Form
Stands for
Relates to
activates
Concept ?
“Tank“

15. Ontology in Computer Science
An ontology is an engineering artifact:
It is constituted by a specific vocabulary used to describe a certain reality, plus
a set of explicit assumptions regarding the intended meaning of the vocabulary.
Thus, an ontology describes a formal specification of a certain domain:
Shared understanding of a domain of interest
Formal and machine manipulable model of a domain of interest
“An explicit specification of a conceptualisation” [Gruber93]

16. Definitions of Ontologies
“An ontology is a formal, explicit specification of a shared conceptualization”
Machine-readable
Consensual
Knowledge
Concepts, properties
relations, functions,
constraints, axioms,
are explicitly defined
Abstract model and
simplified view of some
phenomenon in the world
that we want to represent

17. Ontology
Key components
Class
Property
Individuals
Axiom

18. Class What is a Class? e.g., person, pet, old
a collection of individuals (object, things, )
a way of describing part of the world
an object in the world (OWL Full)

19. Example Classes Class(pp:animal partial
restriction(pp:eats someValuesFrom(owl:Thing)))
Class(pp:person partial pp:animal)
Class(pp:man complete
intersectionOf(pp:person pp:male pp:adult))
Class(pp:animal+lover complete
intersectionOf(pp:person
restriction(pp:has_pet minCardinality(3))))

20. Example Class Class(pp:vegetarian complete intersectionOf(pp:animal
restriction(pp:eats
allValuesFrom(complementOf(pp:animal)))
allValuesFrom(
complementOf(restriction(pp:part_of
someValuesFrom(pp:animal)))))))
DisjointClasses(pp:young pp:adult)

21. Properties What is a Property?
e.g., has father, has pet, service number
a collection of relationships between individuals (and data)
a way of describing a kind of relationship between individuals
an object in the world (OWL Full)

22. Example Properties ObjectProperty(pp:eaten_by)
ObjectProperty(pp:eats inverseOf(pp:eaten_by)
domain(pp:animal))
ObjectProperty(pp:has_pet domain(pp:person)
range(pp:animal))
ObjectProperty(pp:is_pet_of inverseOf(pp:has_pet))
DataProperty(pp:service_number range(xsd:integer))
SubPropertyOf(pp:has_pet pp:likes)

23. Individuals objects in the world
belong to classes (members of the class)
are related to other objects and to data values via properties

24. Example Individuals Individual(pp:Tom type(owl:Thing))
Individual(pp:Dewey type(pp:duck))
Individual(pp:Rex type(pp:dog) value(pp:is_pet_of pp:Mick))
Individual(pp:Mick type(pp:male)
value(pp:reads pp:Daily+Mirror)
value(pp:drives pp:Q123+ABC))
Individual(pp:The42 type(pp:bus)
value(pp:service_number "42“^^xsd:integer))

25. Axiom An axiom is a sentence that is assumed to be true without proof.
Example
If any two animals are siblings, then there exists someone who is the mother of both of them.
with the axiom:
(=> (sibling ?sib1 ?sib2) (exists (?mom) (and (has-mother ?sib1 ?mom) (has-mother ?sib2 ?mom)))

26. Example of a Taxonomy Flight American Airlines Flight Iberia Flight
Subclass-of
Subclass-of
Subclass-of
American Airlines Flight
Iberia Flight
British Airways Flight
Subclass-of
Subclass-of
Subclass-of
Disjoint-Decomposition
Subclass-of
Subclass-of
AA7462
AA2010
AA0488
IB6274
BA0068
BA0066
BA0069

27. Terms glossary

28. Identify Ad-hoc relations
arrival Place
is Arrival Place of
Travel
Location
is Departure Place of
departure Place

29. Define a Concept Dictionary

30. Define in detail Instance Attributes

31. Define Class Attributes

32. Define formal axioms

33. Define Instances

34. An example: Knowledge Web Ontologies
Project
Ontology
Event
Ontology
has associated event
is deliver in / has associated
has person leader
/ leads
has / is associated with
works in / has p p
has associated
is involved in / has p leader
has associated / is associated
is associated with
is WP leader / has person leader
leads / has contractor leader
Person
Ontology
Documentation
Ontology
has involved partner / works in
is author of / has author
participates in / is developed by
has contact person
has Q.A. partner
Organization
Ontology
is contact person / has contact person
has authoring partner
belongs to / is formed by
has lead participant
generates / is generated by

35. Example: Event Ontology
International
Conference
International
Workshop
Management Project
Meeting
KW Area
Meeting
KW Plennary
Meeting
Review
EPMB Meeting
PMB Meeting
Industry Area
Meeting
Research Area
Meeting
Education Area
Meeting

36. Example: Documentation Ontology
Additional
Documentation
Management
Documentation
Technical
Documentation
Thesis
Publication
Templates
Master
Thesis
PhD
Thesis
Manual
Slides
Deliverable
Article
Book
...
Agenda
Cost
Statement EC
Templates
Fax
Mail
Minutes
Periodic
Report
Project
Proposal
...
...
...

37. Example: Relationships between Person, Project and Documentation
Ontology
Deliverable
has associated
is deliver in
Milestone
WP workload
is made up of
has participant
with workload
has
Person
Workpackage
Task
works in
is involved in
leads
is WP leader
Documentation
Ontology
Person
Ontology
is author of
has contact person