- From: Miles, AJ (Alistair) <A.J.Miles@rl.ac.uk>
- Date: Tue, 24 Feb 2004 13:21:54 -0000
- To: "'public-esw-thes@w3.org'" <public-esw-thes@w3.org>
Forwarding this to the list. -----Original Message----- From: Douglas Tudhope [mailto:dstudhope@glam.ac.uk] Sent: 05 February 2004 16:04 To: Miles, AJ (Alistair) Cc: cbinding@glam.ac.uk Subject: feedback on RDF schemas for thesauri and simple KOS *pre-release* Alistair SKOS-CORE looks a very promising start. As promised (belatedly - sorry) some initial comments on these from our point of view (bearing in mind that we don't have much experience in RDF). 1. As you know, we support the idea of allowing for more precise KOS representations. We should also try to maintain compatability with traditional standards. One rationale for the current standard's set of thesaurus relationships is that they are at quite a cost/effective level of generality for many applications, allowing for some user/indexer variation in concept useage and relevance judgements. The proposed scheme does seem to allow for both 'traditional' KOS and more precise, formal constructions which is good. 2. It is important to have some notion of facets but we don't think that current version quite captures it. The scheme correctly takes 'facets' to represent fundamental categories in the sense of Ranganathan, the CRG, BSI standard etc (as opposed to subfacet indicators). Yes, each concept is a member of one and only one facet. But in this sense, I'm not sure it's useful to simply 'treat facets as concepts'? Eg >>> - <rdf:Property rdf:ID="inFacet"> <rdfs:label>member-of-facet</rdfs:label> <rdfs:subPropertyOf rdf:resource="#broader" /> <rdfs:range rdf:resource="#Facet" /> <rdfs:comment> This property indicates that a concept is a member of a facet. A concept may have only one inFacet property. This property is a sub-property of the 'broader' property. Thus faceted conceptual structures may be reduced to simple hierarchical displays by applications that do not comprehend facets.</rdfs:comment> </rdf:Property> >>> a) "This property is a sub-property of the 'broader' property. " -- In particular, we're not convinced about making this relationship a type of the broader relationship. I'd suggest that's not really the semantics? Conceivably subclass/superclass or set membership might be better solutions? b) In any case, we don't quite see how this would realise the degenerate case you describe for non-faceted schemes. Each concept is immediately related by the BT-subtype relationship to its Facet. How does that help you with the degenerate case, where presumably you want the Top of Hierarchy to stand in as a facet? A subclass would do just as well? c) The degenerate case is less important than being able to facilitate more advanced reasoning with faceted schemes. Thus we might wish to use OWL or another language to express facet synthesis rules, or relate thesaurus facets to a higher level ontology. There needs to be a sufficiently clear distinction between facets and member concepts - use of the broader relationship concerns us here. 3. Broader/Narrow - We assume that the OWL representation would formally express the Inverse relationship? However, in the RDF there is nothing to capture the BT/NT connection apart from the comment. Is it useful to make the RDF as self sufficient as possible? Eg would it be useful to introduce a new type of Semantic Relationship called HierarchicalRelationship with BT and NT underneath? We can see this may have drawback of creating additional complexity but suggest as a consideration. 4. Not everyone considers Related (RTs) to be necessarily symmetric (eg the AAT does not). Could 'symmetric' not be an optional property of the relationship? 5. Is there any possibility of defining at least one subtype of Related? Eg a Partitive (see below)? 6. Good to have subtypes of the hierarchical relationships but note that broader/narrowerPartitive is often restricted to members of the same hierarchy (see Aitchison&Gilchrist). In other cases, a Related relationship type is recommended. 7. There is little notion here of the Entry Vocabulary, and the various relationships between concepts and terms. Was there a reason for this? It's a very important aspect of a thesaurus and may(?) be a critical issue for gaining acceptance of a standard in some traditional thesaurus circles. It take it the rationale is http://esw.w3.org/topic/RdfThesaurus - "Suggested solution 2:: We don't bother with them. Instead we offer the recommendation that all acronyms be included as possible labels for a concept. Plural forms probably don't need be included as modern stemming algorithms can identify the root of the term. " a) I see the general point and agree that the longterm solution is making connections with standards in the Linguistic community. However we would tend to argue that relying only on labels results in an impoverished model of a thesaurus? Essentially a thesaurus contains a pragmatic domain-specific lexicon in the entry vocab, equivalence relationships and scope notes. It's one of the reasons why the thesaurus has been such a useful tool over many years and arguably a weakness of some purely concept-based 'ontological' efforts. Could we bring in some version of the Equivalence relationship to SKOS, or alternatively have more properties regarding terms? b) For example, there are various subtypes of equivalence corresponding to parts-of-speech relationships, US/UKalts, types of synonyms, antonyms (even) and these might be distinguished in some future super-KOS systems. Replacing the Equivalnce relationship with a simple 'bag of labels' would lose that possibility. c) Also - in some cases a term will be considered Equivalent to more than one concept (perhaps with different degrees of confidence). Again that becomes less clearly stated. 8. Anyway, be interested to know your thoughts on all this - it's great that someone is proposing possible standards and trying to reach concensus. The general thrust of the SKOS RDF schema is great. What are your plans for progressing it? One way of possibly progressing/discussing some of this effort might be in (or associated with) an NKOS workshop at ECDL'04 in Bath, this September. Marianne Nielsen is aiming to propose a workshop on user-centred issues and this might be a second (or parallel mini-meeting) theme? Hope to get a chance to talk at JISC workshop in London at some point if you are attending for SWAD-Europe demo? regards Doug, Ceri Douglas Tudhope Reader, School of Computing University of Glamorgan Pontypridd CF37 1DL Wales, UK Tel +44 (0) 1443-482271 Fax +44 (0) 1443-482715 dstudhope@glam.ac.uk http://www.comp.glam.ac.uk/pages/staff/dstudhope Editor : The New Review of Hypermedia and Multimedia ----- Original Message ----- From: "Miles, AJ (Alistair)" <A.J.Miles@RL.AC.UK> To: <NKOS@dli2.nsf.gov> Sent: Tuesday, November 25, 2003 1:41 PM Subject: RDF schemas for thesauri and simple KOS *pre-release* > Dear all, > > I offer these schemas as a pre-release, to get some initial feedback and > response on their design. > > SKOS-Core <http://www.w3c.rl.ac.uk/2003/11/21-skos-core> (RDF schema for > encoding thesauri and other simple knowledge organisation systems e.g. > taxonomies and classification schemes.) > > SKOS-Mapping <http://www.w3c.rl.ac.uk/2003/11/21-skos-mapping> (RDF > schema for expressing mappings between concepts from different > thesauri.) > > This work is ongoing in the context of the SWAD-Europe project [1] [2]. > > Yours, > > Alistair Miles. > > [1] SWAD-Europe Thesaurus Activity > <http://www.w3c.rl.ac.uk/SWAD/thesaurus.html> > [2] Semantic Web Advanced Development for Europe project > <http://www.w3.org/2001/sw/Europe/> > > > CCLRC - Rutherford Appleton Laboratory > Building R1 Room 1.60 > Fermi Avenue > Chilton > Didcot > Oxfordshire OX11 0QX > United Kingdom > > Email: a.j.miles@rl.ac.uk > Telephone: +44 (0)1235 445440 >
Received on Tuesday, 24 February 2004 08:22:01 UTC