Introduction to Ontology

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Introduction to Ontology

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Limiting the Scope Ontology Merging/Alignment Mapping, Merging, Alignment Approaches SMART Algorithm Merge Classes (contd..) Merge Classes (contd..) ... – PowerPoint PPT presentation

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Title: Introduction to Ontology

1
Introduction to Ontology

Sudarsun S
Director Research
Checktronix India
Chennai 600010
??????????????????? ??????? ??????????????
?????????????????????? ????????????????

2
Ontology ????????
?????????? ??????????????????
??????????????????????????????????????

???????????????????????????? (????????????????????
???????????)
??????????????????????????
???????????????????????????????
????????????????????????????
???????????????????????????

3
Ontology in Computers

Ontology ??? ???????????????????????
?????????????
??????????????????????????? (????????????????)
????????????????????? ??????????????????
????????????????????????????????????????????
????????????? an ontology ?????
??????????????????????? ????????????????
???????????? ??? ???????????????????????????????
????????????????

4
Example

??????? ??? ???????? (????????)
???? ?????????????????? ?????
??????????? ????????????? ????? ???? ???????????
???????????????????
????????????? ????????????? ???? ????
????????????? 20 ??
????????????????????/????????????????
(?????????????????????????)
????????????? ???? ???????? 2000 ????????
?????????? ???? ???????????? ???? ???????????
????? ????????????? ??????????? ??????????? ???
?????????????

5
Example Ontology (Protégé)
6
What??
7
(No Transcript)
8
Why Ontology?

????????????????????????????????????????????
????????????Software agents
?????????????????????????????????????????????
??????????????????????????????????????????????
???????????????????????????????????????????
??????????????????????????????

9
Few Applications

e-Science, ?????????????? Bioinformatics
The Gene Ontology (GO)
The Protein Ontology (MGED)
Databases
Schema design and integration
Query optimisation
User interfaces
The Semantic Web so-called Semantic Grid

10
Importance towards E-Commerce

Taxonomies provide
?????????????????????????????????? (search
engines, authors, users, databases, programs /
??? agent ???????????????)
Site ????????????? Organization ??? Navigation
?????????????????????? (???? ?????????????????????
???????????)
Umbrella ???????????????????????? (????????
Extension)
???????????? (??????????????? Yahoo!)
Sense disambiguation

11
Importance towards E-Commerce

???????????????????
???????????????
?????????????????????????????????????????????(Inte
roperability)
????????????????????????
?????????????, ???????????????????????????????????
???
Generalization/ Specialization

12
Observations

Ontologies ????????? ?????????????????????????????
?????? ??????
Veritys Topic Editor, Collaborative Topic
Builder, GFP,Chimaeras, Protégé, OIL-ED,etc
Ontologies ??????????????????????????????????
???????????????????? ???? yahoo!, Amazon, excite
Semi-structured sites can provide starting points
Ontologies ?????????????????????????????(?????????
????????????????)
?????????????????????????? ???? Amazon, Yahoo!
Shopping
????????????????????????????????
????????????????????? ????? Markup Languages
XML,RDF
Real ontologies ?????????????????????????
Application

13
Implications Need

????????????????????? Ontology Language
(DAMLOIL)
????????????????????????????????????????
Ontologies
????? (Conceptual Modeling,???????????????????????
??????????, )

14
Issues

?????????? ????????????????????????????
???????????????????????????????????????????
????????????????????
??????
???????
???????????
?????????????
??????????????????? / ??????????????
????????????
?????????
??????????????????????????

15
Chimaera

An interactive web-based tool aimed at
supporting
????????? Ontology (???????????, ???????????,
??????, )
Merging of ontological terms ?????????????????????
?????
?????????? ontologies ????????
?????????????????????????
Features multiple I/O languages, loading and
merging into multiple namespaces, collaborative
distributed environment support, integrated
browsing/editing environment, extensible
diagnostic rule language
????????????????????????????????
??????????? www.ksl.stanford.edu/software/chimaer
a

16
Building Ontology

????? classes
????????????????????? Taxonomic hierarchy
sub-class/super-class model
?????? slots ??? facets ?????? slots
?????????????? slots ???????????

17
Thumb-Rules

??????????????????????????????????????
???????????????????????
?????????????????????????????????????????????????
??????????????
???????????? Ontology ???????? objects(???????/???
????) ??? relationships ???????????????
Objects ??? ???????????
Relationships ??? ???????????????????

18
Step 1 Domain Scope

?????????????????????
???????????????????? Ontology ????
???????????????????????????
?????????????????????????? Ontology ?
?????????????
?????????????????????????????????????
?????????????????????
???????????????????????????????

19
Step 2 Re-Use Existing Ontology

????????????? ????????????????????
?????????? merging Ontologies?
?????????????
??????????????, ????????????????

20
Step 3 Enumerate Terms

Terms ????????
Properties ??? terms ????????
Relationships ??? terms ????????
????????
Animal, elephant, lion
???????, ???????, ???????????
???????????????, ??????????????????????,
???????????????????????

21
Step 4 Define Classes Hierarchy

Top-Down Approach
Bottom-Up Approach
Mixed
Object Oriented Programming Analogy
???????????????????
??????????? Hierarchical ??? concepts
??? class P is a super-class of class Q,
?????????????? B ??? ?????????????? P
??????????? class Q represents a kind-of P

22
Step 5 Properties of Classes - Slots

intrinsic properties ???? softness of silk
extrinsic properties ???? bikes model name
Parts, ??? object ?????????? Structured
?????????????????? physical ??? abstact parts ???
???? ????????????????????????
Relationships ???????????????? class
???? ???? ??? ????????, ?????????????????????????
??????? ???? ????????????????????????
??????????????????

23
Step 6 Define Slots

????? values ??? Slot
??????? ??? slot ??????? values ??????????
????????? Slot
?????????????????????????????
????????????????
String
Number
Boolean
Enumeration
Instance

24
Step 7 Create Instances

?????????????????? instance ???? african_elephant
???????? instance ??? class elephant
High 400 cm
Weight 6,500 Kg
Eat fruit, leaf (instance of food class)
Behavioer aggressive
Kind Herbivore (instance of animal_type class)

25
Consistency Checks ??

????????????? Class hierarchy ???????
????????????????????????????? tree ???????
???????????????????
classes ?????????????????????? ??????????????
class
???????????????? is-a ??? kind-of
??????????????????????????????
Multiple Inheritance

26
Consistency Checks ??

?????????? class ?????????????????
???????? Subclass ??? class ???????????
??????????????????????? super-class ?????
??????????????????????? super-class
???????????? relationships ????????? super-class
??
Class ???? ???? property-value ?????
class african_elephant ???? class elephant
????? property type ???? african
????????????????????????????????
???? Instance ???? Class?
Individual Instances ???? ????????????????????????
????????
??? concept ?????????????????????????????????
?????? classes

27
Limiting the Scope

??????????????????????????????????????????????????
???????????
???????????????????????????? ???? ?????????
?????????????????????????????????
?????????????????? properties ????????????????????
?? ?????????????? ?????? classes ?? hierarchy

28
Ontology Merging/Alignment

??????????????
?????????????????????????????????????
????????????????????? ontology merging and
alignment
?????????????? (????????????????????)
???????????????? merging and alignment
????????????????????????

29
Mapping, Merging, Alignment
30
Approaches

????????????????????????? merging
?????????????
??????????????????????
?????????????
??????????????????? merging
???????????????????????
????????????????????
?????????????????????????????????
???????????????????????????????????????
????????????? ????????????

31
SMART Algorithm
32
Merge Classes (contd..)
33
Merge Classes (contd..)
34
Suggestions (contd..)
35
Source Car Rental
36
Source Airline Reservation
37
(No Transcript)
38
Features

?????????????????????
????????
??????????????????????????
???????????????????
??????????????????????
????????????????????????????????????????????????
??????????????????????
?????????????????????????????
?????????????????????

39
Ontology Languages - RDF

RDF ??? Resource Description Framework
???? W3C candidate recommendation
(http//www.w3.org/RDF
RDF ???? graphical formalism (XML syntax
semantics)
??????????????????????????????????????????????????
??????????????????????????????????????????????????
??????????
RDFS extends RDF ??? schema vocabulary??????????
??
Class, Property
Type, subClassOf, subPropertyOf
Range, domain

40
RDF Syntax --Triples
Subject
Object
Property
Ex Subject
Ex Object
Ex Property
41
RDF Syntax --Triples
Subject
Object
Property
Ex Subject
Ex Object
Ex Property
_ xxx
42
RDF Syntax --Triples
Subject
Object
Property
Ex Subject
Ex Object
Ex Property
_ xxx
43
RDF Syntax --Triples
Subject
Object
Property
Ex Subject
Ex Object
Ex Property
_ xxx
_ yyy
44
RDF Syntax --Triples
Subject
Object
Property
Ex Subject
Ex Object
Ex Property
_ xxx
_ yyy
ltlt plain litteral gtgt
45
RDF Syntax --Triples
Subject
Object
Property
Ex Subject
Ex Object
Ex Property
_ xxx
_ yyy
ltlt plain litteral gtgt
ltlt lexical gtgtdata type
46
RDF Syntax -- Graph
_ xxx
47
RDF Syntax -- Graph
ltlt Palani Ramasamy gtgt
Ex name
_ xxx
rdf type
Ex Person
48
RDF Syntax -- Graph
ltlt Palani Ramasamy gtgt
Ex name
_ yyy
_ xxx
Ex member-of
rdf type
Ex Person
49
RDF Syntax -- Graph
ltlt Palani Ramasamy gtgt
ltlt University of Madras gtgt
Ex name
Ex name
_ yyy
_ xxx
Ex member-of
rdf type
rdf type
Ex Organisation
Ex Person
50
RDFS
51
RDFS

RDFS vocabulary adds constraints on models, e.g.
x,y,z type(x,y) subClassOf(y,z) type(x,z)

52
RDFS

RDFS vocabulary adds constraints on models, e.g.
x,y,z type(x,y) subClassOf(y,z) type(x,z)

Ex Person
Ex Animal
rdf subClassof
53
RDFS

RDFS vocabulary adds constraints on models, e.g.
x,y,z type(x,y) subClassOf(y,z) type(x,z)

Ex Person
Ex Animal
rdf subClassof
Ex John
Ex Person
rdf type
54
RDFS

RDFS vocabulary adds constraints on models, e.g.
x,y,z type(x,y) subClassOf(y,z) type(x,z)

Ex Person
Ex Animal
rdf subClassof
Ex John
Ex Person
rdf type
rdf type
Ex Animal
55
Problems with RDFS

RDFS ?????????????????????????????????????????????
?????
?????????????? ????????????? range ??? domain
?????????????????? ????????? hasChild ??? person
????????????????? person and elephant
???????????????????? elephants
????????????? existence/cardinality
?????????????????? ??????????? person ?? 1 mother
??????? mother ???? 1 person ??????? ???? person
?? 2 parents ???????????????
?????????????? transitive, inverse ????
symmetrical
?????????????????? isPartOf ????????????
transitive, isPartOf ??? inverse ??? isPartOf ???
touches ??? symmetrical
????????????????? ??????????????
????? native reasoners ??????
??????????????????????
May be possible to reason via FO axiomatisation

56
Axiomatisation

An Axiomatisation ??????????????? RDFS ?? FOL,
????????
Triple x P y translated as holds2 (P,x,y)
Axioms capture ????????????????? language
???????? axiomatisations include
????????? set ????????????????? ??? axioms
????????????????????????????????? captured
????????????
Axiomatisation ???????????????????????????
complexity
RDFS ? undecidable (subset of) FOL
????? interoperability ?????? ??????????
axiomatised ????????????
???? C subClassOf D equivalent to
??????? axiomatise ???? holds2(subClass, C, D)

57
RDF to OWL

????????????????????? extending(????????????) RDF
OIL Ontology Inference Layer
DAML-ONT DARPA Agent Markup Language
??????????Merged ?????????? DAMLOIL
Extends (DL subset of) RDF
DAMLOIL
Web-Ontology(WebOnt) Working Group formed
WebOnt group ??????????? OWL Language based on
DAMLOIL
OWL language now a W3C Proposed Recommendation

58
Description Logics

???????????????? logic based Knowledge
Representation formalisms
??????????? semantic networks ??? KL-ONE
??????????????????????? concepts(classes),
roles(properties, relationships) ??? individuals
???????????????
Formal semantics (????????????????????????????????
????)
?????????????????????????? FOL
??????????????????????????????? Prepositional
Model Dynamic Logics
??????????????? inference services
??????????????????????????????????????????
(???????????, ???????????, ???)
Implemented systems (highly optimized)