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Dynamic Aspects of SEKT Legal Ontologies
Zhisheng Huang, Stefan Schlobach, Frank van Harmelen
Vrije University Amsterdam
Nuria Casellas and Pompeu Casanovas
Universitat Autonoma de Barcelona
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Outline
• SEKT Legal Ontologies
• Ontology Versioning: Motivation
• Prototype of MORE (Multi-version Ontology REasoner)
• Quantitative/Qualitative Analysis
• Conclusion
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SEKT Legal Case Study
•Design an intelligent system to help new judges with their practical problems:
• Intelligent FAQ system using Semantic Web technologies
•Connect the iFAQ system with the existing judgments
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Ontologies used in Legal Case
• OPJK (Ontology of Professional Judicial Knowledge)• 104 classes, 567 instances
• Topic ontologies:• QTO (Questions Topic Ontology)
• 17 topics
• JTO (Judgments Topic Ontology)• 30 topics.
• Judgment Ontology• 15 terms, integrated in PROTON
See Mercedes’ talk tomorrow for details.
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OPJK and Versioning• Modelled from the questions extracted from
the ethnographic survey• Aprox. 850 questions, 700 terms
• OPJK was being built extracting relevant concepts and relations from one question at a time (grouped in subdomains)
• There are a lot of versions as additions took place and modifications were required during modeling for keeping track of OPJK for it's changes.
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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.
• Change Tracking: Keep track of ontology changes.
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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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Abstract Use Cases
• Semantic Change Log (Temporal logic)• Summary of changes in the deductive closure
• Compatibility Checking (Temporal logic)• Compare results of queries against expected
answers
• Version Selection (Hybrid Logic)• Check versions for certain required statements
• Version Planning (Dynamic Logic)• Simulate the impact of possible changes
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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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Linear Time Logic LTLm
• Operators: • Boolean operators: negation, conjunction, etc.• Temporal operators (Backlooking operators)
• Prev : holds in the previous version• P: holds in a prior
version(Sometimes in the past)• H: holds in all prior versions (Always
in the past) S: always holds in the prior versions
since holds in a prior version
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Semantics
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Reasoning Queries
: holds in the current version Prev : holds in the current
version but no 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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Reasoning Query: last version I
holds at the last version in which holds .
S (Prev( ))
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Effect Space
• Effect space is the set of all possible semantic relations in a version space.
• In MORE, we consider effect spaces which are characterized by the new/obsolete/invariant relation on concepts/roles/individuals on a version space.
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Retrieval Queries
• child/parent/descendant/ancestor concept relations
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The MORE System
• Functionality• Temporal Reasoning Queries• Ontology Comparison Queries:• Versioning Retrieval Queries• Ontology Data format: OWL, RDF/RDFS
and DIG
• http://wasp.cs.vu.nl/sekt/more
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Dynamic Aspect: New
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Dynamic Aspect: Stability
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Dynamic Aspect: Nonmonotonicity
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New at Concept Level
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Stability at Concept Level
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Qualitative Evaluation I
• Stable change of OPJK: S (H).
descendant(Fuerzas_de_Orden_Público, Objeto) S (H descendant(Fuerzas_de_Orden_Público,
Objeto) ).
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Qualitative Evaluation II
• Last version detection:
S (Prev( ))
descendant(Fuerzas_de_Orden_Público, Organización) S (Prev
descendant(Fuerzas_de_Orden_Público, Organización) descendant(Organización, Grupo)).
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Conclusions
• We studied the properties of the overall versioning space by checking for stability, novelty and monotonicity of the process.
• More detailed analysis on dynamic aspects at concept level
• We provided an initial case study on the stability of change in the versioning space using the power of the temporal logic which underlies MORE.