Transforming and extending classification systems – UDCC Seminar

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Estimated reading time 2–3 minutes

This post is the last in a series about the UDC consortium international seminar in The Hague, 19-20 September, 2011

Joan S. Mitchell, OCLC (USA), and Marcia Lei Zeng, Kent State University (USA), supported by Maja Žumer, University of Ljubljana (Slovenia), talked about extending models for controlled vocabularies to classification systems: modelling DDC with FRSAD, which led to interesting discussions about their concepts of “nomen” and “thema”.

Along with my former colleague Andy Heather, now CTO at DODS Parliamentary Communications Ltd, I talked about our work on the data migration of classifications from a legacy database into new taxonomy management software, presenting our paper: Transformation of a legacy UDC-based classification system: exploiting and remodelling semantic relationships.

Conclusions

The key ideas I took away from the conference were:
1) Classifications and ontologies are not an either/or choice. They have different properties and different strengths and weaknesses and so should be chosen according to the task in hand.
2) It is difficult to turn a classification into an ontology, but easy to turn an ontology into a taxonomy, so if you don’t have either to start with and can’t decide, an ontology is a safer bet. If you already have a classification, you need to think carefully about whether it is worth turning it into a fully modelled ontology, as converting it to RDF or SKOS is likely to be much easier. However, at the moment, RDF and SKOS have limitations, especially in handling faceted taxonomies, so beware of losing semantic richness in the conversion process. Polyhierarchies offer a way of expressing facets in SKOS.
4) Vocabulary control and alignment continue to be significant issues for the Semantic Web.
5) Ontology curation, management, and semantic alignment will be increasingly important issues for the Semantic Web.

Slides and audio recordings of all 21 talks can be now downloaded from the conference website.

Conference proceedings are published by Ergon Verlag and can now be
purchased/ordered online from http://seminar.udcc.org/2011/php/proceedings.php.

Classification and ontology in specific subjects – UDCC Seminar

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Estimated reading time 3–5 minutes

Day two of the UDC consortium international seminar opened with two subject-specific talks – Wolfram Sperber described a classification of mathematics and Andrew Buxton showed how similar chemistry classification and ontologies are, using the ChEBI ontology. He also described the different ways classifications and ontologies could be used to support each other and about the lack of good graphical tools and visualisations to represent ontologies.

Categories and relations: key elements of ontologies – Categorial Distinctions

Roberto Poli, University of Trento (Italy) talked about the compliexisties of part-whole relationships. There are simple wholes, composed of a sum of their parts, but some parts of wholes cannot simply be added together – for example, the social, psychological, and physical aspects of a person. He also discussed the difference between science as epistemological – dealing with what can be known – and ontological – deraling with what exists.

Towards a relation ontology for the Semantic Web

Dagobert Soergel made a bold claim that the only way for the Semantic Web to deliver its promise is if we adopt a relation ontology and map each dataset to the standard, to allow interoperability. He pointed out that you “do not getting semantics from syntax alone”.

Relations in the notational hierarchy of the Dewey Decimal Classification

Rebecca Green from OCLC described the difficulties encountered when trying to automatically create ontologies from the Dewey Decimal Classification. These included semantic differences in the way subclasses had been defined, meaning that no single rule would handle them all appropriately.

Modelling concepts and structures in analytico-synthetic classifications

The eminent Ingetraut Dahlberg compared Aristotle and Ranganathan’s key facets and UDC and Colon Classification systems. She also presented a survey of academic subject areas analysed into facets.

Representing the structural elements of a freely faceted classification

Claudio Gnoli of the University of Pavia, talked about freely faceted classifications, in comparison with systems such as UDC. He emphasised the urgency of publishing classifications on line, but highlighted the limitations of SKOS and OWL to fully expressed faceted systems despite the fact that faceted systems are extremely good tools for obtaining precise search results. Faceted systems are also excellent for combining information across disciplines, allowing you to combine aspects of one subject areas with aspects of a different one, and interdisciplinarity is becoming increasingly important as an approach, as innovation often happens at the boundaries between disciplines.

He pointed out that a polyhierarchical approach can be modelled in SKOS as a way of representing facets, but that this approach is often overlooked. He also called for more work to be done on SKOS so that it can represent facets directly.

Facet analysis as a tool for modelling subject domains and terminologies

Vanda Broughton, University College London, offered the Bliss Classification as a useful tool for online subject classification, but called for help in how best to publish it for general use. Should it be released as a text document, database, or should work be done to convert it to an ontology – and if so, in what form?

She stressed how the logical approach of facet analysis and regular syntax makes it predictable and hence ideal for machine manipulation.

Analytico-synthetic approach for handling knowledge diversity in media content analysis

Devika P. Madalli, Indian Statistical Institute, DRTC (India), described the Living Knowledge project that used an analytico-synthetic approach in order to bring together around useful themes diverse content from different sources using varied means of expression. This supported a rich faceted search system.

Slides and audio recordings of all 21 talks can be now downloaded from the conference website.

Conference proceedings are published by Ergon Verlag and can now be
purchased/ordered online from http://seminar.udcc.org/2011/php/proceedings.php.