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Reasoning with Multi-version Ontologies:

a temporal logic approach

Zhisheng Huang and Heiner Stuckenschmidt

Vrije University Amsterdam

The Netherlands

ISWC2005 http://sekt.semanticweb.org/

Outline

• Motivation

• Framework

• Temporal logics

• Examples

• Prototype of MORE (Multi-version Ontology REasoner)

• Data Test and Evaluation

• Conclusion and Future work.

ISWC2005 http://sekt.semanticweb.org/

Multi-versioning: Why

• Change Recovery: allow the possibilities for the developers to withdraw or adjust the changes to avoid unintended impacts.

• Compatibility: Ontology users may prefer an earlier version with less resource requirement to a newer version with higher resource requirement.

• ……

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The Idea of Versioning

• Version Spaces: • Models resulting from changes are stored separately • Models and change operations form a graphcalled

Version Space• Data is accessed through the “right” version

v1 v3

v2 v4

v6

v5

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Managing Version Spaces

• Idea: Enable Administrator to ask questions about the version space

• Combine Reasoning: • Ontologies: DL reasoner (RACER) • Version Space: Modal Logic

• Principle: • Each Ontology is a possible world • Truth of statements in a state is determine by

the DL reasoner

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Simplifying Assumptions

• Linear Time Temporal Logic• Linear Version Space• Operators

• Conjunction, Negation, PreviousVersion, AllPriorVersions

• Pre-defined Statement predicates• Child-of, parent-of,• Any other RACER function..

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Version Space

• Version space: A version space S over an ontology set Os is a set of ontology pairs, namely, S Os × Os.

• Linear version space: S = {<o1, o2>, <o2, o3>, · · · , <on−1, on>} such that oi oj for i j.alternatively, we write

S=(o1, o2, …, on)

• Linear ordering: o’< o iff o’ occurs prior to o in the sequence S.

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Linear Time Logic LTLm

• Operators: • Boolean operators: negation, conjunction, etc.• Temporal operators (Backlooking operators)

• Prev : holds in the previous version (PreviousVersion)

• P: holds in a prior version(Sometimes in the past) (SomePriorVersion)

• H: holds in all prior versions (Always in the past) (AllPriorVersions)

S: always holds in the prior versions since holds in a prior version (Since)

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Semantics

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Formal Properties

• H -> P .

• H -> Prev .

• Prev -> P.

• Prev P -> P .

• P P -> P .

• H H -> H .

• Prev Prev -> P .

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Reasoning Queries

: holds in the current version Prev : holds in the current

version but not in the previous version.

P: incompactible (with respect to ).

H : holds only in the current version, it never holds before.

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Reasoning Query: stable change

• Once is changed, it is never changed again.

S (H).

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Change Accounting: Only Twice

is changed only twice.

S Prev( S H).

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Change Accounting: Only N times

• Change(1, ) =df S H.

• Change(n, ) =df S Prev(Change(n-1,)).

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Reasoning Query: last version I

holds at the last version in which holds .

S (Prev( ))

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Reasoning Query: last version II

holds at the last version in which does not hold before a version holds.

S (Prev( S Prev( ))).

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Retrieval Queries

• child, parent concept relation

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Relative Versioning

• Version0 . (the current version)

• Version-i Prev(Version -(i-1) )

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Absolute Versioning

•Version(i,S) Version i-n

where |S|=n

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Retrieval Query

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The MORE System

• Milestone 3.5 – Software Prototype• .• Prototype: MORE (Multi-version Ontology REasoner)• MORE website: http://wasp.cs.vu.nl/sekt/more

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The MORE System

• Functionality• Temporal Reasoning Queries• Ontology Comparison Queries:• Versioning Retrieval Queries• Ontology Data format: OWL and DIG

• Test Data• BioSAIL ontologies (3 versions)• SEKT legal case study ontologies (5

versions)

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A Query Answer

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Test Result: Change Log

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Conclusions

• A framework of multi-version ontology reasoning

• Temporal logic approach

• Expressive power of LTLm

• Semantic differences on multi-version ontologies.

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Future Work

• Integrating MORE with ontology evolution (Dynamic logic approach).

• Branching time version space.