Towards Integrating Ontologies An EDM-Based Approach

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Towards Integrating Ontologies An EDM-Based Approach

  1. 1. Towards Integrating Ontologies An EDM-Based Approach Evelyn Dröge, Julia Iwanowa, Violeta Trkulja, Steffen Hennicke, Stefan Gradmann Berlin School for Library and Information Science, Humboldt-Universität zu Berlin Presentation on the 13th International Symposium of Information Science Potsdam, 21.03.2013co-funded by the European Union
  2. 2. DM2E projectDigitised Manuscripts to Europeana (DM2E)• EU-funded Europeana satelite project• Duration: Three years (2012 – 2015)• Partners from Germany, Austria, Norway, Greece, UK and Italy• Primary aims: To enable as many content providers as possible to get their data into Europeana and to stimulate the creation of new tools and services for reuse of Europeana data in the Digital HumanitiesIBI at the Humboldt-Universität zu Berlin• Coordinates the project• Is further involved in modeling and in evolving the technical infrastructure 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 2
  3. 3. DM2E: Interoperability approach• Base: Semantic Web and Linked Data – Enable and facilitate data interoperability – Share and reuse ontologies• Build on common data models – EDM, DC and DCTerms, OAI-ORE, CIDOC-CRM, FOAF, SKOS – BIBO, VOID, FABIO• Uses W3C standards – RDF(S), OWL Enable data interoperability 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 3
  4. 4. Why should we reuse ontologies?• Nature of Linked Data• Reduce multiple likewise resources• Better visibility of the ontology• Better quality of the ontology• Better integration into the Linked Open Data Cloud• Easy access for more applications• Make it easier for others to reuse the vocabulary 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 4
  5. 5. Reuse practice• Three steps workflow 1. Ontology retrieval 2. Integration-oriented ontology evaluation  Identification of suitable classes and properties  Analysis of missing elements 3. Ontology integration  Different methods Simperl, 2010 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 5
  6. 6. Steps in the Reuse Workflow
  7. 7. Step 1: Ontology retrieval 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 7
  8. 8. Step 2: Integration-oriented ontology evaluation DC • Which elements are missing or can be rdaGr2 DCTerms replaced? • What are suitable EDM SKOS classes or properties in other standards or FOAF vocabularies? ORE 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 8
  9. 9. Step 3: Ontology integrationFour different methods can be used for reusing ontologies: 1. Direct adoption of external resources • External classes or properties are directly used in the ontology buildup. • Can be used if the external class or property exactly matches the own resource. • Definitions or labels should not be adjusted! 2. Reuse of external resources without original URIs • The name of a foreign property or class is used without its original namespace. 3. Reuse of external resources with integration into ontology hierarchy • Properties or classes are created in the own namespace. • Subproperty or subclass relations are built between them and the external resource. 4. Referring to external resources via equivalence properties •owl:equivalentClass or owl:equivalentProperty are used to refer to equivalent external resources. 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 9
  10. 10. Integrating ontologies:Method comparison 3 Indirect Integration 4 Direct 2 1 Integration Original URI New URI 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 10
  11. 11. Further Insight into the Integration Methods
  12. 12. 1. Method:Direct adoption of external resources• Example: dm2edata:exampleItem edm:type text ; bibo:isbn „978-3-86680-192-9“ .  Integrating bibo properties for describing text objects• When should the method be used? – If the meaning and definition of the external resource is identical to the meaning of the own resource.• Advantages and Disadvantages + Pro: Reduces the amount of resources that describe the same thing in other words. − Con: The method is also used when the meaning is not exactly the same, which can lead to conflicting descriptions. 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 12
  13. 13. 1. Method:Direct adoption of external resourcesExample: foaf:Document Document Physical Thing ? Dokument Abstract Class ? Document@en Electronic? Documents 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 13
  14. 14. 1. Method:Direct adoption of external resourcesExample: Some properties of foaf:Documentrdfs:label Document Document@en Retrieved from the Linked Open Documentation@en Vocabularies SPARQL endpoint: document@en http://lov.okfn.org/endpoint/lovdc:title Document@endcterms:identifier foaf:Documentation @en-gbrdfs:comment A document. An abstract class defining any kinds of publishing work.@en The foaf:Document class fully represents the ADMS concept of documentation.@en Similar to the Agent concept, we have again decided to include a concept from the popular FOAF ontology. The FOAF Vocabulary Specification currently defines Document in a very loose way: The foaf:Document class represents those things which are, broadly conceived, documents. ... We do not (currently) distinguish between physical and electronic documents, or between copies of a work and the abstraction those copies embody." […]vann:usageNote Used in ADMS specifically for the class of documents that further describe a Semantic Asset or give guidelines for its use. ADMS expects all documents to have a title (use dcterms:title).^^ 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 14
  15. 15. 2. Method: Reuse with new URIs• Example: Different URIs for the class thing owl:Thing gold:Thing  Are they identical or equivalent?• Advantages and Disadvantages + Pro: Can be used as a first step in the construction process if other vocabularies are not known. − Con: It is not clear how the different classes can be set into relation and it makes it hard to query or reuse the vocabulary.• This method should not be used! 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 15
  16. 16. 3. Method: Reuse with subrelations• Example: dm2e:Agent rdfs:subClassOf foaf:Agent . dm2e:publishedAt rdfs:subPropertyOf dcterms:spatial .  New dm2e property and class as subelements• When should this method be used? – If an existing class or property is found which is broader defined than the resource that should be created.• Advantages and Disadvantages + Pro: The new property or class can have its own description. + Pro: Broader properties or classes are easy to be found in upper ontologies . 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 16
  17. 17. 4. Method: Reuse with equivalence properties• Example: edm:Event owl:equivalentClass crm:E4.Period . prism:issn owl:equivalentProperty bibo:issn .  Reference to equivalent resources• When should this method be used? – If exactly the same individuals can be part of all equivalent classes or can be connected with all equivalent properties.• Advantages and Disadvantages + Pro: The elements can have different descriptions. − Con: Not every tool can interpret the equivalence properties. 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 17
  18. 18. Ontology Reuse in DM2E
  19. 19. Background: The EDM and its specialisationsThe EDM (Europeana Data Model)… builds the backbone of Europeana… unites several standards and vocabularies… covers the representation of cultural heritage objects from libraries, archives and museums… is as generic as possible… can be specialised for different domains 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 19
  20. 20. Reusing practice in EDM and DM2E• Reuse in EDM Primarily used – Method 1: Direct integration • Problem: Definitions may differ – Method 4: Use of equivalence properties Used for additional classes• Reuse in DM2E – Method 1: Direct integration • Here: Use of additional DM2E scope notes that add information about the reuse of the integrated element in DM2E – Method 3: Adding resources with subproperties • If the new resource has a narrower definition – Method 4: Use of equivalence properties • Analogue to the EDM for additional classes or properties 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 20
  21. 21. Reusing practice in EDM and DM2E II• Example: Methods 1 and 3 DC EDM DM2E dc:contributor dc:contributor dm2e:contributor rdfs:subPropertyOf dc:contributor Range: Not restricted. Range: Person, Range: Person as an URI organisation or service. of type edm:Agent. Definition: „An entity that Definition: „An agent that Definition: „A person that is responsible for making is responsible for making is responsible for making contributions to the contributions to the contributions to the resource.“ resource.“ resource.“ 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 21
  22. 22. Conclusion• Reuse in DM2E: Mixture of all methods (excluding method 2)  Making use of the method that suits best• There is not one „best method“ for all reuse cases… … but contradictions in descriptions can be avoided even if resources are reused!• What we did not (yet) cover: „When owl:sameAs is not the same…“  Problems that might occur when there are too many different understandings of resource meanings 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 22
  23. 23. Thank you for your attention!Evelyn DrögeJulia IwanowaBerlin School for Library andInformation ScienceHumboldt-Universität zu Berlinwww.ibi.hu-berlin.deDigitised Manuscripts to Europeanawww.dm2e.euevelyn.droege@ibi.hu-berlin.dejulia.iwanowa@ibi.hu-berlin.de 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 23
  24. 24. ReferencesLiterature• Berners-Lee, T. (2006). Linked Data - Design Issues. W3C Website. http://www.w3.org/DesignIssues/LinkedData. [03.03.2013]• Halpin, H., & Hayes, P. J. (2010). When owl:sameAs isn’t the Same: An Analysis of Identity Links on the Semantic Web. Proceedings of the WWW2010 Workshop on Linked Data on the Web, LDOW 2010, Raleigh, USA, April 27, 2010, CEUR Workshop Proceedings (Bd. 628).• Heath, T., & Bizer, C. (2011). Linked Data: Evolving the Web into a Global Data Space. Synthesis Lectures on the Semantic Web: Theory and Technology (Bd. 1). Morgan & Claypool.• Simperl, E. (2010). Guidelines for Reusing Ontologies on the Semantic Web. International Journal of Semantic Computing, 04(02), 239–283.Images• Footstep (Slide 6): http://openclipart.org/detail/left-footprint-by-anonymous• Magnifier (Slide 11): http://openclipart.org/detail/159469/web-search-grayscale-by- sibskull• Document (Slide 13): http://info.docuvantage.com/Portals/61671/images/stack%20of% 20files%20photo_istock.jpg• Ontology (Slide 19): http://openclipart.org/detail/133363/ontology-by-imad• IBI (Slide 23): http://commons.wikimedia.org/wiki/File:Berlin,_Mitte,_Dorotheenstrasse, _Handelskammer_Berlin_02.jpg 21.03.2013 Towards Integrating Ontologies: An EDM-Based Approach 24

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