Automatic creation of mappings between classification systems for bibliographic data

Transcription

1 Automatic creation of mappings between classification systems for bibliographic data Prof. Magnus Pfeffer Stuttgart Media University

2 Agenda Motivation Instance-based matching Current implementation Experimental evaluation Further work October 14th, 2016 DC

3 Motivation October 14th, 2016 DC

4 Current situation in Germany Five regional library unions Subject headings Predominantly RSWK ( Regeln für den Schlagwortkatalog - Rules for the subject catalogue ) using a shared authority file Classification systems RVK (Regensburg Union Classification) BK (Basic Classification) DDC (Dewey Decimal Classification) Various local classification systems Low proportion of indexed titles (25-30%) October 14th, 2016 DC

5 Current situation in Germany National library Subject headings Predominantly RSWK ( Regeln für den Schlagwortkatalog - Rules for the subject catalogue ) using a shared authority file Classification systems DDC (Dewey Decimal Classification) Coarse categories DDC only for titles published since 2007 Only Reihe A (print trade publications) is fully indexed with RSWK October 14th, 2016 DC

6 Mapping: Goals Re-use existing indexing information National level BK is used mainly in northern Germany RVK mainly in southern Germany DDC mainly by the National Library International level Make RVK data more accessible to DDC users Use DDC indexing information available from e.g. the Library of Congress October 14th, 2016 DC

7 Mappings: Application ideas Use of appropriate classification systems Facetted search in resource discovery systems Should be monohierarchical Should have limited number of classes DDC (first digits) or BK Browsing of similar titles Should be fine-grained DDC (full) or RVK Multi-lingual retrieval October 14th, 2016 DC

8 Mappings: Application ideas Enable the use of existing tools and visualisations Denton (2012) Legrady (2005) October 14th, 2016 DC

9 Current projects Coli-conc Coordinated by the Gemeinsamer Bibliotheksverbund Library union of the states in northern Germany Aim: Exhaustive concordances from DDC to other library classification systems Main work on DDC RVK mapping Mainly manual mapping Use of statistical analysis Development of software to support mapping process October 14th, 2016 DC

10 Current projects Austrian National Library Manual creation of mappings from RVK BK Very time-consuming process Several partial mappings completed Enrichment of local data Titles with existing RVK classification are enriched with BK classes from mapping Main use-case: Facetted browsing of large result lists in the resource discovery system See Plößnig (2014) October 14th, 2016 DC

11 Instance-based matching October 14th, 2016 DC

12 Ontology matching Well-studied problem in computer science Several approaches Based on the descriptors Based on the structure Based on the manifestations (instances) October 14th, 2016 DC

13 Instances Entries in catalogues with multiple classifications October 14th, 2016 DC

14 Instance-based matching Assumptions Classes with semantic overlap appear together The more often these classes co-occur, the stronger the overlap Preparation Extraction of all pairs of classifications from the data Analysis of the extracted pairs October 14th, 2016 DC

15 Example October 14th, 2016 DC

16 Normalisation Comparing absolute numbers is useless Some classes are used more often than others Number of pairs correlates with the number of entries that are classified using a given class Instead: Use proportion of co-occurrence single occurrence E c1 E c2 E c1 E c2 number of entries with both classifications divided by number of entries with either classification (Jaccard measure for overlap of sets) October 14th, 2016 DC

17 Prior and related work Isaac (2007), Schopman (2012) Application of instance-based matching in the library domain Several projects using data from the Dutch national library Exhaustive analysis of different statistical measures Overall very encouraging results Probstmeyer (2009) Application of instance-based matching to German library data Mapping classification system to index terms October 14th, 2016 DC

18 Current implementation October 14th, 2016 DC

19 Challenges Lack of dually annotated items BK and RVK annotations located in different library union catalogues Austrian data already contains enrichment results Scaling Merging data from all German catalogues results in >100 million records International open data catalogs should be included as well October 14th, 2016 DC

20 Clustering Multiple editions Multiple document types October 14th, 2016 DC

21 Clustering Skewed data Multiple editions More pairs Some co-occurrences could appear stronger than others Solution: Pre-clustering individual titles on the work level Each cluster contributes only once Benefit: Increases chance for instances with more than one classifications October 14th, 2016 DC

22 Scaling Fast clustering Based solely on author and title information Generates and stores match keys and key equivalences for each record Generates the full closure of equivalent keys by iterating over the key equivalences Backend All software uses basic key-value access and search features Allows use of different NoSQL products to adapt to local infrastructure October 14th, 2016 DC

23 Experimental evaluation October 14th, 2016 DC

24 Data sets Library union catalogs with BK or RVK data All Entries Monographic entries Monographic with RVK Monographic with BK GBV 32,027,977 24,267, ,976,154 SWB 18,789,185 16,447,890 4,383,273 0 BVB 26,680,083 23,658,674 7,215,483 0 October 14th, 2016 DC

25 Data results Clusters Using only authors and corporate bodies (no editors, other persons) Using only main title or uniform title (no subtitles) 21,653,606 clusters 904,876 contain both BK and RVK annotations Co-occurrence 1,155,552 different RVK-BK pairs October 14th, 2016 DC

26 Evaluation Parameters Jaccard-like measure: the ratio of clusters with a given RVK-BK classes pair clusters containing the RVK class (we are only looking for RVK BK mappings) Absolute number of clusters with a given pair Gold standard Partial mapping RVK BK from the field of economics Manually created by a domain expert analysing class descriptions and structure October 14th, 2016 DC

27 Precision num num num num num num October 14th, 2016 DC

28 Recall num num num num num num October 14th, 2016 DC

29 f-measure num num num num num num October 14th, 2016 DC

30 Additional analysis All mappings from 0.6 and number 6 that were not part of the manual gold standard Manual analysis by reading class descriptions Results: 49 pairs 31 considered to be correct 12 partially correct 1 false 5 contained RVK classes that are no longer in active use Usable for improvement of manual mapping October 14th, 2016 DC

31 Results Combined data contains enough annotation information to use instance-based methods Very robust, fast and scalable implementation Encouraging results from comparison to gold standard Potential fur further improvement October 14th, 2016 DC

32 Future work October 14th, 2016 DC

33 More! More bibliographic data National catalogs International catalogs Bibliographies More experiments Different clustering parameters Different statistical analysis October 14th, 2016 DC

34 Share! Publish open source code Implement data import stage in a data modelling toolkit, e.g. knime.org Test different open source backends Publishing results in an accessible format October 14th, 2016 DC

35 Thank you for listening. Slides available online This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License. October 14th, 2016 DC

36 References Isaac, Antoine, Lourens van der Meij, Stefan Schlobach, and Shenghui Wang (2007). An empirical study of instance-based ontology matching. In Karl Aberer (Editor), The Semantic Web. 6th International Semantic Web Conference, 2nd Asian Semantic Web Conference, ISWC ASWC 2007, Busan, Korea, November 11-15, 2007, (Lecture Notes in Computer Science, 4825). Berlin: Springer Plößnig, Veronika; Christoph Steiner (2014). Klassifikationen: Konkordanzen, Anreicherungsprojekte und RVK - Datenkorrekturen im Österreichischen Bibliothekenverbund. Ein Update. Retrieved September 12th, 2016, from regensburg.de/34088/1/ppt%20plnig_steiner-rvk-bk- October pdf 14th, 2016 DC