X-SOM X-SOM A Flexible Ontology A Flexible Ontology Mapper Mapper Carlo Curino, Giorgio Orsi, Letizia Tanca {curino,orsi,tanca}@elet.polimi.it Politecnico di Milano Dipartimento di Elettronica e Informazione September 4 th SWAE 2007 (DEXA’07) Regensburg
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X-SOMX-SOMA Flexible Ontology A Flexible Ontology
MapperMapperCarlo Curino, Giorgio Orsi, Letizia Tanca
{curino,orsi,tanca}@elet.polimi.it
Politecnico di MilanoDipartimento di Elettronica e Informazione
September 4th
SWAE 2007 (DEXA’07)Regensburg
SWAE 2007
MotivationsMotivationsPart of the Context-ADDICT Project (Context Aware Data Design Integration Customization and Tailoring).
Scenarios:Scenarios:• Ontology-based integration of heterogeneous data sources• Semantic Web applications• Knowledge Management
• From matchings to mappings: The debugging process.
• Experimental Results.
SWAE 2007
The ProblemThe Problem
AlignmentAlignment
Ontology AlignmentOntology Alignment:: The process of bringing two or more ontologies into mutual agreement, by relating their constitutive elements by means of alignment relationships, and making them coherent and consistent..
SWAE 2007
The ProblemThe Problem
MatchinMatchingg
Ontology AlignmentOntology Alignment:: The process of bringing two or more ontologies into mutual agreement, by relating their constitutive elements by means of alignment relationships, and making them coherent and consistent..
SWAE 2007
The ProblemThe Problem
MappingMapping
Ontology AlignmentOntology Alignment:: The process of bringing two or more ontologies into mutual agreement, by relating their constitutive elements by means of alignment relationships, and making them coherent and consistent.
SWAE 2007
X-SOM’s mapping processX-SOM’s mapping process
Matching:Matching: Similarities between ontologies computed with a customizable set of matching algorithms (strategy). The results are combined by means of a feed-forward neural network.
Debugging:Debugging: Matchings are tested for consistency and coherency to improve their quality. Conflicts are solved in a (semi-)automatic fashion.
Mapping:Mapping: An ontology containing the mappings between the constitutive components of the input ontologies.
• Learned function robust to domain changes, but• It is not robust to different design techniques. The network learns the intrinsic reliability of the
matching algorithms (and their combinations).
• Training set: • The number of samples with positive and negative
outcomes must be balanced.• The techniques influence each others: selection of
almost independent techniques.
SWAE 2007
Matchings debuggingMatchings debugging• Semantic consistency checking: The process of verifying whether there are mappings that modify the semantics of the elements belonging to the original ontologies.
• Debugging process:
• Guarantees satisfiability while preserving the semantics of the original ontologies.• Makes use of heuristics and of an extended tableau algorithm for description logics to allow matching debugging and explanation.• Addresses multiple mappings.
Conclusion and Future WorkConclusion and Future Work
• Summary:• We presented an extensible ontology mapper that combines
several matching algorithms by means of a neural network and uses a debugging process to improve the quality of ontology mappings as well as guarantee the consistency of the mapping.
• We tested its performance against the OAEI’07 benchmarks.
• Future Work:• Increase mappings expressiveness (Heterogeneity / GLAV).• New modules: e.g., pure structural matchers, instance and
instance-based matchers.• How can collaborative background knowledge improve mapping
algorithms?
SWAE 2007
Question timeQuestion time
Q & A(If I’m showing this slide, I haven’t run out of time)
SWAE 2007
SWAE 2007
Overall System ArchitectureOverall System Architecture
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Models viewModels view
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Data TailoringData TailoringData Tailoring, based on the Data Tailoring, based on the Dimension Tree Dimension Tree InstantiationInstantiation::• Schema Tailoring• Instance Tailoring
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Semantic ExtractionSemantic Extraction
Data Source Ontology:• Semantic Extraction: data abstract model + storage model• Supports the query processing• Models isolation (different models can be used separately)