An Introduction to Ontology, Ontology Merging, Mapping, and Alignment

1
An Introduction to Ontology, Ontology Merging,
Mapping, and Alignment

• Farhad Mostowfi

2
What is Ontology?

• Ontologies have been developed to share knowledge
  between people and heterogeneous and distributed
  systems 1.

3
What is Ontology? (Cont.)

• Ontology evolves as the knowledge in the field
  evolves.

• Ontology incorporates semantics.

• Ontologies enable building knowledge-intensive
  applications.

• Ontology provides a domain theory and not the
  structure of a data container 2.

4
Ontology Components

• A set of concepts
• A set of properties
• A set of relational properties
• An acyclic relation called concept hierarchy
  (subconcept/superconcept relation)

5
Ontology Components (Cont.)

• An acyclic relation called property hierarchy
  (subproperty/superproperty)
• A subset of symmetric properties
• A subset of transitive properties
• A symmetric relation that relates inverse
  relational properties

6
Ontology Components (Cont.)

• The set of domain concepts for some property
• The set of range concepts for some relational
  property
• minimum and maximum cardinality for each
  concept-property pair

7
Ontology Languages on the Web 3
8
Expressivity of Ontology Languages
9
What will happen next?

• Can we get everybody to agree on a single
  ontology for a domain or a sub-domain?
• Can we make people to adopt our ontology?
• Can we have everybody to use the same language to
  implement his ontology?
• Can we have people to use the same logical
  notion?

10
What will happen next? (Cont.)

• So we need methods and tools to help in
  integrating and combining ontologies that have
  been implemented differently in every aspect.

11
Mismatch between ontologies

• language level mismatches
• Syntax
• logical representation
• Semantic of primitives
• Language expressivity
• ontology level mismatches
• How to interpret a domain
• How to model the interpretation

12
Other Mismatching Issues

• Versioning
• Identification of intended definitions
• Change tracking
• Conversion from one version to another.
• Repeatability
• Back tracking on how certain decisions have been
  made

13
Different Ways of Integrating Ontologies

• Merging
• Creating a new ontology from two or more existing
  ontologies
• Mapping
• Relating similar concepts or relations
• Aligning
• Bring two or more ontologies into mutual agreement

14
Comparison between ontology Combining systems
15
Conclusion

• The importance of integrating ontologies and
  versioning
• So many different ontology languages and not
  enough aligning and merging tools
• Scalability problem of available tools

16
References

• 1 Michel Klein, Dieter Fensel, Frank van
  Harmelen, and Ian Horrocks. The Relation
  between Ontologies and XML Schemas, Linkoping
  Electronic Articles in Computer and Information
  Science, 6(4), (2001)
• 2 M. Klein. Combining and relating ontologies
  an analysis of problems and solutions. In
  IJCAI-2001 Workshop on Ontologies and Information
  Sharing, pages 53--62, Seattle, WA, 2001
• 3 OWL Web Ontology Language Overview.
  http//www.w3.org/
• 4 A. Maedche and B. Motik and L. Stojanovic.
  Managing Multiple and Distributed Ontologies in
  the Semantic Web. Managing Multiple and
  Distributed Ontologies in the Semantic Web. VLDB
  Journal, Special Issue on the Semantic Web (in
  the process of being published)
• 5 H. Sofia Pinto, A. Gomez-Perez, and J. P.
  Martins. Some Issues on Ontology Integration. In
  Proceedings of IJCAI99's Workshop on Ontologies
  and Problem Solving Methods Lessons Learned and
  Future Trends, pages 7.1--7.12, 1999

17
(No Transcript)