Use Case Browsing And Searching In Repositories With Different Thesauri

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Browsing and searching in data repositories annotated with different thesauri


Klaas Dellschaft

Background and Current Practice

In the library community, there exist different thesauri for annotating entries in library catalogues. Examples are the Dewey Decimal Classification, Library of Congress Subject Headings and the German Schlagwortnormdatei.


Given that appropriate mappings between the thesauri are provided, a user should be able to browse and search in several library catalogues in parallel with the keywords from any of the used thesauri, i.e. the result list should also contain entries which have been annotated with corresponding keywords from the mapped thesauri.

Target Audience

General public, librarians.

Use Case Scenario

The user Bob wants to search for books about a certain topic. Bob uses the catalgoue system of his local library. Bob thus formulates an appropriate query using the category system and the thesaurus of his local library (e.g. his local library uses the category system of the German National Library and the German Schlagwortnormdatei).

Unfortunately, his local library has no books covering the searched topic. Bob thus also wants to search in the catalogues of further libraries which are participating in the interlending system. But some of the other libraries use another category system and thesaurus (e.g. the Dewey Decimal Classification and/or the Library of Congress Subject Headings). Thus, his original query has to be transformed in order to search in the catalogues of all libraries participating in the interlending system.

This transformation is automatically done by the catalogue system of his local library using a mapping between the different categorization systems and thesauri. The system then returns a ranked list of relevant results from the searched library catalogues.

Application of linked data for the given use case

In order to support the above use case, it is important that there exist mappings (i.e. links) between the different thesauri and categorization systems. Providing this as linked open data, it becomes easier to integrate further thesauri and or categorization systems into the network of interlinked thesauri.

Existing Work (optional)

The German National Library offers the German Schlagwortnormdatei also as linked open data. This data includes mappings to other vocabularies like the Dewey Decimal Classification.

Related Vocabularies (optional)

SKOS, Dublin Core.

Problems and Limitations

A major problem of the current SKOS specification is that it is not clear how to provide mappings between a pre-coordinated and a post-coordinated vocabulary. But this kind of mapping is required for being able to use one (e.g. post-coordinated) vocabulary for also retrieving resources which have been annotated with another (e.g. pre-coordinated) vocabulary.

At least three steps are required for enabling the above scenario:

1) The SKOS specification has to be extended in order to be able to also represent coordinated concepts. 2) In case of post-coordinated vocabularies, it has to be defined how to annotate complex topics to resources. 3) It has to be clarified how to interpret mappings between "simple concepts" and "coordinated concepts" during the retrieval.

Related Use Cases and Unanticipated Uses (optional)

Library Linked Data Dimensions / Topics

References (optional)

Documentation of the linked data service of the German National Library (German). Includes a description of how the mapping between the German Schlagwortnormdatei and the Dewey Decimal Classification have been achieved.