Talk at Semantic Technologies Conference 2006 (March 6-9, San Jose)

1. Change Management and
Versioning in Ontologies
Baden Hughes
Department of Computer Science and Software Engineering
The University of Melbourne
Parkville VIC 3010, Australia
badenh@csse.unimelb.edu.au
© 2005 Your name here The University of Melbourne
Baden Hughes /

2. Agenda
Definitions
Ontology Change
Typology of Change
Practical Matters
Change-Aware Tools
Conclusion
2
© 2005 Your name here.

3. Definitions
Ontology = specification of a
conceptualisation of a knowledge domain
(Gruber, 1993)
OWL = OWL Lite and OWL DL, although
many principles also hold for OWL-Full
3
© 2005 Your name here.

4. Ontology Change
© 2005 Your name here The University of Melbourne
Baden Hughes /

5. Why Ontologies Change
Ontology change induced by
– domain changes
– adaptations to different applications
– changes in conceptualization or
understanding
Ontologies have a general tendency to
have more changes the earlier they are in
their lifecycle
Modularized ontologies have a general
tendency to change asynchronously
5
© 2005 Your name here.

6. Real World Ontology Change:
UNSPSC
UN Standard Products and Service Code
(UNSPSC), http://unspsc.org/
– “An open, global multi-sector standard for
efficient, accurate classification of products
and services”
– Primarily targeted at e-commerce
UNSPSC change history
– 16 updates between 1/2001 and 9/2001
– Each update contained between 50 and 600
changes
– In 7.5 months, >20% of the “standard” is
changed 6
© 2005 Your name here.

7. Tracking Change: Comparison or
Versioning ?
Ontology versioning
– mechanism to store and identify various versions of the
same ontology and highlight their differences.
Ontology comparison
– helps knowledge managers to locate changes between
different versions of an ontology
If conceptual relations between different versions are
constructed, it becomes possible to re-interpret the data and
knowledge under different ontology versions
– Semantic, rather than syntactic resolution
Non-dynamic response to changes in ontologies may affect
the use of these ontologies by higher level applications.
– Applications need to update their logic to reference the
new ontology.
7
© 2005 Your name here.

8. Typology of Change
© 2005 Your name here The University of Melbourne
Baden Hughes /

9. Generic Changes
Change types
– Non-logical change
– Logical definition change
– Identifier change
– Addition of definitions
– Deletion of definitions
Extent of change
– Transformation or actual change
– Conceptual relation
– Descriptive meta-data like date, author, and
reason of the update
– Valid context
9
© 2005 Your name here.

10. Example Ontology Changes (for OWL)
Hierarchy
– Adding a class or property
– Removing a class or property
– Merging two classes or properties
– Splitting a class into two classes
Class
– Renaming a class
– Changing label, comment or cardinality of a class
– Changing parent
– Removing parent
– Adding a child
– Removing a child
– Adding a property to a class
– Removing a property from a class
10
© 2005 Your name here.

11. Example Ontology Changes (for OWL)
Properties
– Renaming a property
– Changing the domain
– Changing the range
– Changing the sub-property reference
– Changing label or comment
Other change types
– Property characteristics
– Equality or inequality
– Restricted cardinality
– Union or intersection
11
© 2005 Your name here.

12. Practical Matters
© 2005 Your name here The University of Melbourne
Baden Hughes /

13. Change Management Processes
Logical that ontology changes should be
handled like other types of (software)
changes
– Proposal, review, evaluation,
implementation
Distributed authoring and maintenance
poses a challenge for treating ontologies
this way
Application level dependencies
(particularly reasonings) also need to be
considered as well
13
© 2005 Your name here.

14. Naming and URIs (for OWL)
Naming ontologies and ontology versions
– Assign a URI to the ontology and to
each version of the ontology
– Use a convention when constructing
URIs for ontology versions and apply it
consistently
Naming of classes and properties
– Do not use ontology version URIs to
construct URIs for clases and properties
– The ontology may have identified
versions, but the ontology version URIs
are not used to construct new class or
property URIs at each version
14
© 2005 Your name here.

15. Version Metadata (for OWL)
Where URIs have been allocated to the
ontology and also to each ontology
version, generic (DublinCore) metadata
can assert formal relations
• dc:isVersionOf and dc:hasVersion
If the ontology version is also an formal
ontology then OWL’s own versioning
constructs can be used
• owl:priorVersion and
owl:backwardsCompatibleWith
• owl:versionInfo is also possibility
15
© 2005 Your name here.

16. Deprecation Metadata (for OWL)
Where a replacement has been made,
generic DublinCore metadata
– dcterms:replaces and
dcterms:isReplacedBy
– NB these are not formally asserted
relations
owl:DeprecatedClass and
owl:DeprecatedProperty can be used to
state that a class or property should no
longer be used
16
© 2005 Your name here.

17. Change Logs
In contrast with the open formats used for
many popular ontologies (eg XML based
representations), many ontology editing
tools
– Use proprietary formats for change logs
– Document informally specified changes
Many ontology editing tools only partially
record changes
There is no substitute for a traditional
version control system in conjunction with
an ontology editing environment
17
© 2005 Your name here.

18. Some Change-Aware Tools
© 2005 Your name here The University of Melbourne
Baden Hughes /

19. Protégé
Dominant ontology editor/browser
Reasonable features for ontology change
management and versioning
– Undo/Redo with command history
– Version archiving with time-stamping
and comments
PROMPT plug-in for multiple ontology
management
• Compare, move, merge, extract
Formal change logging (machine
readable)
19
© 2005 Your name here.

20. OntoView
Structure based comparison for ontologies
Supports unique identifiers and
persistence of change
Differentiation at formal definition,
comment, conceptualization vs explication
Interactive user support
Export formal translations and
transformations
Automated inconsistency checking
20
© 2005 Your name here.

21. SWOOP
Web-based ontology browser and editor
Capture and annotation mechanism for
atomic ontology changes
Enables exchange of changes amongst
community of users
Human, not machine targeted
21
© 2005 Your name here.

22. LINGOES/OntoChange
Architecture for ontology management
based on OntoGloss, RDF data store,
change management process and a UI
Formal specification of change types
Formal representation of changes (delta)
Rules for traversing changes
Version hierarchy
22
© 2005 Your name here.

23. Others
SHOE
– Formal versioning and backwards
compatibility
PromptDIFF
– Fixed-point algorithm and
implementation (partially in Protégé)
CONCORDIA
– Retirement for concepts and concept
versioning; type hierarchy impact tracing
SemVersion
– Structural and semantic versioning
23
© 2005 Your name here.

24. Conclusions
© 2005 Your name here The University of Melbourne
Baden Hughes /

25. Open Issues
Is the relationship between increasing formality of
expression and change impact entirely
predictable?
Heavy modularization of ontologies is largely
inefficient in dissipating effects of changes
Is developing an ontology of change is possibly
an effective counter-measure to unpredicted high-
impact changes ?
Can we more effectively adopt methodologies for
change management and versioning from
software and data engineering ?
Is ontology change management more a socio-
technical problem rather than purely technical
problem ?
25
© 2005 Your name here.

26. Parting Thoughts
The state of the art in change
management and versioning in ontologies
is not particularly advanced
Theoretical development of models for
change is still continuing
Tool support is emerging, but lacks
cohesion around a single methodology
Robust ontology-dependent application
instances are difficult to achieve
Change impact amelioration strategies can
dissipate downstream effects of changes
26
© 2005 Your name here.

27. Key References
Heflin & Hendler, 2000. Dynamic Ontologies on the Web. Proc. AAAI-
2000.
Klein & Fensel, 2001. Ontology Versioning on the Semantic Web.
Proc. Intl. Semantic Web Working Symp.
Klein, Kiryakov, Ognyanov & Fensel, 2002. Finding and Characterizing
Changes in Ontologies. Proc. 21st Intl. Conf. on Conceptual Modelling.
Noy & Klein, 2003. Ontology Evolution: Not the Same as Schema
Evolution. Knowledge and Information Systems 5.
Noy & Musen, 2004. Ontology Versioning in an Ontology Management
Framework. IEEE Intelligent Systems 19(4).
Liang, Alani, Shadbolt, 2005. Change Management: The Core Task of
Ontology Versioning and Evolution. Proc. PREP 2005.
Liang, Alani, Shadbolt, 2005. Ontology Change Management in
Protégé. Proc. AKT DTA Colloquium.
Mostowfi & Fotouhi, 2005. Change in Ontology and Ontology of
Change Proc. K-CAP 2005 Workshop on Ontology Management.
27
© 2005 Your name here.

28. Offline Q&A, Contact Info
Baden Hughes
Department of Computer Science and Software Engineering
The University of Melbourne
Parkville VIC 3010, Australia
badenh@csse.unimelb.edu.au
© 2005 Your name here The University of Melbourne
Baden Hughes /