Change Management and Versioning in Ontologies

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

Change Management and Versioning in Ontologies

Baden HughesDepartment of Computer Science and Software Engineering

The University of MelbourneParkville VIC 3010, Australia

[email protected]

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© 2005 Your name here.

AgendaDefinitionsOntology ChangeTypology of ChangePractical MattersChange-Aware ToolsConclusion

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DefinitionsOntology = specification of a conceptualisation of a knowledge domain (Gruber, 1993)OWL = OWL Lite and OWL DL, although many principles also hold for OWL-Full


Ontology Change

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Why Ontologies Change

Ontology change induced by – domain changes– adaptations to different applications– changes in conceptualization or

understandingOntologies have a general tendency to have more changes the earlier they are in their lifecycleModularized ontologies have a general tendency to change asynchronously

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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

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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 ontologyIf 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.


Typology of Change

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Generic ChangesChange types– Non-logical change

– Logical definition change

– Identifier change

– Addition of definitions

– Deletion of definitionsExtent of change– Transformation or actual change– Conceptual relation– Descriptive meta-data like date, author, and

reason of the update– Valid context

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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

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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


Practical Matters

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Change Management Processes

Logical that ontology changes should be handled like other types of (software) changes– Proposal, review, evaluation,

implementationDistributed authoring and maintenance poses a challenge for treating ontologiesthis wayApplication level dependencies (particularly reasonings) also need to be considered as well

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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 URIsare not used to construct new class or property URIs at each version

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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

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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

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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 changesThere is no substitute for a traditional version control system in conjunction with an ontology editing environment


Some Change-Aware Tools

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Protégé

Dominant ontology editor/browserReasonable features for ontology change management and versioning– Undo/Redo with command history– Version archiving with time-stamping

and commentsPROMPT plug-in for multiple ontology management

• Compare, move, merge, extract

Formal change logging (machine readable)

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OntoView

Structure based comparison for ontologiesSupports unique identifiers and persistence of changeDifferentiation at formal definition, comment, conceptualization vs explicationInteractive user supportExport formal translations and transformationsAutomated inconsistency checking

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SWOOP

Web-based ontology browser and editorCapture and annotation mechanism for atomic ontology changesEnables exchange of changes amongst community of usersHuman, not machine targeted

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LINGOES/OntoChange

Architecture for ontology management based on OntoGloss, RDF data store, change management process and a UIFormal specification of change typesFormal representation of changes (delta)Rules for traversing changesVersion hierarchy

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Others

SHOE– Formal versioning and backwards

compatibilityPromptDIFF– Fixed-point algorithm and

implementation (partially in Protégé)CONCORDIA– Retirement for concepts and concept

versioning; type hierarchy impact tracingSemVersion– Structural and semantic versioning


Conclusions

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Open IssuesIs the relationship between increasing formality of expression and change impact entirely predictable?Heavy modularization of ontologies is largely inefficient in dissipating effects of changesIs 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 ?

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Parting Thoughts

The state of the art in change management and versioning in ontologiesis not particularly advancedTheoretical development of models for change is still continuingTool support is emerging, but lacks cohesion around a single methodologyRobust ontology-dependent application instances are difficult to achieveChange impact amelioration strategies can dissipate downstream effects of changes

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Key ReferencesHeflin & 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.


Offline Q&A, Contact Info

Baden HughesDepartment of Computer Science and Software Engineering

The University of MelbourneParkville VIC 3010, Australia

[email protected]

Technology

Change Management and Versioning in Ontologies