30.10.06 Krzysztof Janowicz SIM-DL -Towards a Semantic Similarity Measurement Theory for the...
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30.10.06 Krzysztof Janowicz
SIM-DL-Towards a Semantic Similarity Measurement Theory for the Description Logic ALCNR in Geographic Information Retrieval
Krzysztof JanowiczInstitute for Geoinformatics; University of Münster
Krzysztof Janowicz SIM-DL (for ALCNR) 2
Outline
• Motivation: Yet Another Similarity Theory?
• Similarity & Subsumption based IR
• Matching Scenario
• SIM-DL Framework
• Human Subject Testing
• Results, Conclusions & Outlook
Krzysztof Janowicz SIM-DL (for ALCNR) 3
Yet Another Similarity Theory?
Available ontologies (DL!)Available theories
Measured between (re)representation!
http://flickr.com/photos/genista/25390358/
Krzysztof Janowicz SIM-DL (for ALCNR) 4
Similarity & Subsumption based Retrieval
Krzysztof Janowicz SIM-DL (for ALCNR) 5
Similarity vs. Subsumption
• Subsumption-based Retrieval(+) Results fit user’s requirements (subconcepts!)(-) Too generic / too specific result set(-) Artificial search concept
• Similarity-based Retrieval(+) Search concept = searched concept(-) Results not necessarily fit user’s requirements
Krzysztof Janowicz SIM-DL (for ALCNR) 6
Matching-Scenario
• Accommodation web portal
• External services (SOA)
• Use shared base vocabulary
• Local interface and terminology
• Hotel, Houseboat, Youth Hostel, Botel,….
Task: Integrate Amsterdam-Accommodation Service
Where to put botels?
Krzysztof Janowicz SIM-DL (for ALCNR) 7
Houseboats, Hotel &Botel
Krzysztof Janowicz SIM-DL (for ALCNR) 8
Some Impressions
Pictures received by email, taken from wikipedia and http://www.hotels.nl/amsterdam/botel/
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SIM-DL: Representation (ALCNR)
Krzysztof Janowicz SIM-DL (for ALCNR) 10
SIM-DL: Framework
1. Specify search concept and context
2. Rephrase concepts to canonical NF
3. Generate alignment matrix
4. Apply sim-functions for selected combinations
5. Derive normalized overall similarity
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SIM-DL: Search Concept & Context
(-) Results not necessarily fit user’s requirements
Define Context
Clcs ≡ Housing
Cs ≡ Botel
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Rephrase Concepts to Canonical NF
• ALCNR Normal Form:
+ Rewriting rules (e.g. R() ≡ (≤ 0 R))
+ Minimal set of descriptions (concepts)
Canonical Normal Form
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Generate Alignment Matrix
• Cartesian Product Cs Ct
CsiCsj
Csk
Cti N … …
Ctj … … H
Ctk … CO …
Ctl … … …
HierarchiesNeighborhoodsCo-Occurrence
H > N > CO
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Apply Similarity-Functions (for selected combinations)
• Individual similarity functions for each DL language constructor:{union, intersection, role-intersection, existential
quantification, value restriction, cardinality}
• For Hierarchies, Neighborhoods, Co-Occurrence
edge_distancemax_distance
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Amalgamated & Normalized Overall Similarity
• Union-Constructor:Weighted sum of similarities on CNF union levelWeightings derived from A-Box, T-Box or A&T-Box
• Intersection-Constructor:Sum of similarities on CNF intersection levelNormalization to [0,1]
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Human Subject Testing: Roles & Fillers
Auto. weighted average (>)
Multiplicative approach (<)
User input
Disjoint from watercourse Meets river
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Results, Conclusion & Outlook
• SIM-DL combines subsumption and similarity
• Adapts results from psychology & computer science Cognitive Engineering ;-)
• Only basic model of Alignment and Context
• More Human Subject Tests needed
• More expressive DL
• Usability?
( )ALCRP DALCNRNear ?
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30.10.06 Krzysztof Janowicz
Questions? Thanks for your attention!
Visit www.similarity-blog.de for related literature.
From: http://www.jobblog.ch/sommer-250