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RE: [SKOS] About Closing ISSUE-36 ConceptSchemeContainment

From: Miles, AJ \(Alistair\) <A.J.Miles@rl.ac.uk>
Date: Fri, 18 Jan 2008 17:10:40 -0000
Message-ID: <677CE4DD24B12C4B9FA138534E29FB1D0499DF7F@exchange11.fed.cclrc.ac.uk>
To: "Antoine Isaac" <aisaac@few.vu.nl>
Cc: "SWD WG" <public-swd-wg@w3.org>

Dear Antoine,

A new Editors' Draft of the SKOS Reference is available at:

[1] <http://www.w3.org/2006/07/SWD/SKOS/reference/20080118>

This draft includes a new appendix E as a placeholder for SKOS/SPARQL patterns. 

The preamble to this appendix states the following:

"""This section describes some patterns for using the SPARQL query language [@@REF-SPARQL-QUERY] to implement some common operations required by applications that use SKOS data. All of these patterns are consistent with the SKOS data model."""
 
A sketch has been included of a pattern in which names of concept schemes are used as names of RDF graphs, allowing the containment of a semantic relation to be queries, with the caveat that this might not be appropriate for more advanced versioning scenarios.

Section 4.6.3. in the main body of the document provides a brief statement of our position wrt concept schemes and named RDF graphs, with a link to more detailed information in the new appendix E. 

The originally proposed text (below) has not been used verbatim, because the document does not define a formal notion of conformance (see section 1.7), and therefore the keywords MAY and SHALL are hard to interpret -- it is not used anywhere else in the document (none of the BCP 14 key words are used).

However, appendix E hopefully makes it clear that all of the documented SKOS/SPARQL patterns are consistent with the SKOS data model.

Note also that [1] does not make any statement about recommended practice wrt rdfs:isDefinedBy. If that is considered within scope for this document, then I suggest we raise an issue specifically devoted to that and consider it for subsequent drafts.

I hope this addresses your concerns.

Kind regards,

Alistair.
	
--
Alistair Miles
Research Associate
Science and Technology Facilities Council
Rutherford Appleton Laboratory
Harwell Science and Innovation Campus
Didcot
Oxfordshire OX11 0QX
United Kingdom
Web: http://purl.org/net/aliman
Email: a.j.miles@rl.ac.uk
Tel: +44 (0)1235 445440  

> -----Original Message-----
> From: public-swd-wg-request@w3.org 
> [mailto:public-swd-wg-request@w3.org] On Behalf Of Antoine Isaac
> Sent: 15 January 2008 20:57
> To: SWD WG
> Subject: Re: [SKOS] About Closing ISSUE-36 ConceptSchemeContainment
> 
> 
> Hello,
> 
> Regarding my action on ISSUE-36 [1]. It seems that my mail 
> [4] was a bit too panicky.
> As a reminder, the complete text of ISSUE-36 reads:
> 
> > SKOS defines a 'concept scheme' as: "a set of concepts, optionally 
> > including statements about semantic relationships between 
> those concepts."
> >
> > SKOS relationships such as broader and narrower are represented as 
> > triples in RDF. The fact that a particular broader/narrower 
> > relationship between two concepts belongs to a concept 
> scheme cannot 
> > then be represented without resorting to reification.
> >
> > A principled approach to representing this containment 
> would be desirable.
> 
> 
> One can indeed select/adapt from [2, 3, 4] the following material:
> 
> =============== Beginning of text
> 
> Vocabulary: skos:ConceptScheme, skos:inScheme, skos:hasTopConcept
> 
> Axiomatic Triples:
> skos:ConceptScheme rdf:type owl:Class.
> skos:inScheme rdf:type owl:ObjectProperty skos:inScheme 
> rdfs:range skos:ConceptScheme skos:hasTopConcept rdf:type 
> owl:ObjectProperty skos:hasTopConcept rdfs:domain 
> skos:ConceptScheme skos:hasTopConcept rdfs:range skos:Concept 
> skos:ConceptScheme owl:disjointWith skos:Concept
> 
> skos:ConceptScheme denotes the class of SKOS concept schemes. 
> Beyond this statement, there are no further semantics 
> conditions on the interpretation of skos:ConceptScheme.
> 
> This specification does not make any statement about the 
> formal relationship between the class of Concept Schemes and 
> the class of Named RDF Graphs. The decision not to make any 
> such statement has been made to allow different design 
> patterns to be explored for using SKOS with query languages 
> such as SPARQL. @@For more information about recommended 
> patterns for using SKOS with SPARQL, see SECTION@@ In 
> particular, skos:ConceptScheme MAY be interpreted as a 
> sub-class of the class of named RDF graphs. This would allow 
> to use the name (URI) of a concept scheme in SPARQL queries 
> as the name of a graph, to establish the containment in this 
> concept scheme for a semantic relationship between two SKOS 
> conceptual resources.
> Notice that this interpretation would not be appropriate, 
> however, if different named RDF graphs were used to express 
> different "states" or "versions" of a concept scheme; or if a 
> concept scheme were interpreted as having alternative 
> expressions, as an RDF graph and an HTML document for example 
> (in which case separate URIs might be required for the 
> concept scheme, the RDF graph, and the HTML document).
> 
> skos:ConceptScheme MAY also be interpreted as a sub-class of 
> owl:Ontology. This would be consistent with using owl:imports 
> to make logical import statements between SKOS concept schemes.
> 
> It is also possible to use rdfs:isDefinedBy to explicitly 
> state the relationship between a SKOS conceptual resource and 
> the concept scheme in which it is defined.
> However, for the purpose of stating the relationship between 
> a SKOS conceptual resource and the concept scheme(s) to which 
> it belongs, which is a different goal, the skos:inScheme 
> property shall be used.
> 
> =============== End of text
> 
> I think this gives an answer to ISSUE-36.
> Notice that I've made is to replace "provenance" by 
> "containment" in the following sentence from [2]
> >
> > In particular, skos:ConceptScheme MAY be interpreted as a 
> sub-class of 
> > the class of named RDF graphs. This would allow to use the 
> name (URI) 
> > of a concept scheme in SPARQL queries as the name of a graph, to 
> > establish the provenance of a semantic relationship between 
> two SKOS 
> > conceptual resources.
> 
> I've done this to better fit the ISSUE. Please say if this 
> has consequences I have overlooked...
> 
> Best,
> 
> Antoine
> 
> [1] http://www.w3.org/2006/07/SWD/track/issues/36
> [2]
> http://www.w3.org/2006/07/SWD/wiki/SkosDesign/ConceptSchemes/M
> inimalProposal?action=recall&rev=1
> [3] http://www.w3.org/2006/07/SWD/SKOS/reference/20071223
> [4] 
> http://lists.w3.org/Archives/Public/public-swd-wg/2008Jan/0019.html
> 
> 
Received on Friday, 18 January 2008 17:11:05 UTC

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