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AW: RE : substitute for skos:isSubjectOf

From: Neubert Joachim <J.Neubert@zbw.eu>
Date: Fri, 23 Jan 2009 15:39:29 +0100
Message-ID: <3A59BB6451C972429019B12996F92DAD0239233F@frodo.zbw-nett.zbw-kiel.de>
To: "Antoine Isaac" <Antoine.Isaac@KB.nl>, "Houghton,Andrew" <houghtoa@oclc.org>, <public-esw-thes@w3.org>
Hi Antoine,
 
I agree with you that it's perfectly possible to query a SPARQL server either way round. In a closed world, there would be no problem. But the usage I want to encourage is the "follow-your-nose" principle Ed Summers described for the web of open linked data. This modus operandi makes heavy use of the fact that RDF forms a directed graph. Navigation through this graph in a straightforward way is possible only in the direction given by the existing triples. And with dc:subject (or any other relation that puts the concept in the object position), it is the wrong direction. So, when you are at the node of the concept, you come to nowhere without having the inverse relation materialized. - I hope this may explain my stubbornness about this issue ... 
 
Cheers, Joachim



________________________________

	Von: Antoine Isaac [mailto:Antoine.Isaac@KB.nl] 
	Gesendet: Freitag, 23. Januar 2009 11:32
	An: Houghton,Andrew; Neubert Joachim; public-esw-thes@w3.org
	Betreff: RE : substitute for skos:isSubjectOf
	
	

	Dear Joachim,
	
	First a quick question: why would you be so upset about descriptor in the object position?
	In RDF --especially when you want to query an RDF graph with SPARQL-- there is no fundamental difference between having asserted a triple (r1,p,r2) and the triple (r2,p',r1), when p' is the inverse of p. (apart of course if one of your resources is a literal, but that's not your case)
	
	Cheers,
	
	Antoine
	
	-------- Message d'origine--------
	De: public-esw-thes-request@w3.org de la part de Houghton,Andrew
	Date: jeu. 22/01/2009 18:27
	: Neubert Joachim; public-esw-thes@w3.org
	Objet : RE: substitute for skos:isSubjectOf
	
	Yes, that's what I meant.  dct:relation says that there is a relationship between the skos:Concept and another URI given by rdf:Description.  The dct:subject is a property of the URI given by rdf:Description.  One could have split this out to be:
	
	
	
	<rdf:Description rdf:about="http://www.econis.eu/...=Black+market">
	
	  <dct:subject rdf:resource="http://zbw.eu/stw/descriptor/19289-4" />
	
	</rdf:Description>
	
	
	
	<skos:Concept rdf:about="http://zbw.eu/stw/descriptor/19289-4">
	
	  <skos:prefLabel>Black market</skos:prefLabel>
	
	  <dct:relation rdf:resource="http://www.econis.eu/...=Black+market" />
	
	</skos:Concept>
	
	
	
	and if RDF encountered another definition some where in your data or any data you merged with, such as:
	
	
	
	<rdf:Description rdf:about="http://www.econis.eu/...=Black+market">
	
	  <dct:title>Black market search</dct:title>
	
	</rdf:Description>
	
	
	
	it would merge the dct:title and dct:subject under the http://www.econis.eu/...=Black+market URI.
	
	
	
	
	
	Andy.
	
	
	
	From: Neubert Joachim [mailto:J.Neubert@zbw.eu]
	Sent: Thursday, January 22, 2009 12:13 PM
	To: Houghton,Andrew; public-esw-thes@w3.org
	Subject: AW: substitute for skos:isSubjectOf
	
	
	
	So, the example you built would look like this:
	
	
	
	 <skos:Concept rdf:about="http://zbw.eu/stw/descriptor/19289-4 <http://zbw.eu/stw/descriptor/19289-4> ">
	
	    <skos:prefLabel>Black market</skos:prefLabel>
	
	    <dct:relation>
	
	      <rdf:Description rdf:about="http://www.econis.eu/...=Black+market <http://www.econis.eu/...=Black+market> ">
	
	        <dct:subject rdf:resource="http://zbw.eu/stw/descriptor/19289-4" />
	
	      </rdf:Description>
	
	    </dct:relation>
	
	  </skos:Concept>
	
	
	
	Right, so far? The meaning, as I understand it, would be two statements about two different subjects:
	
	
	
	http://zbw.eu/stw/descriptor/19289-4 has a dct:relation to http://www.econis.eu/...=Black+market, and
	
	http://www.econis.eu/...=Black+market has a dct:subject of http://zbw.eu/stw/descriptor/19289-4
	
	
	
	I'm not sure if I got this right -
	
	
	
	Joachim
	
	
	
	       
	________________________________
	
	
	        Von: Houghton,Andrew [mailto:houghtoa@oclc.org]
	        Gesendet: Donnerstag, 22. Januar 2009 17:14
	        An: Neubert Joachim; public-esw-thes@w3.org
	        Betreff: RE: substitute for skos:isSubjectOf
	
	        Yup, I totally didn't understand what you meant.   I thought http://zbw.eu/stw/descriptor/19289-4 was the bibliographic resource not the concept.  However given that new information it's just a matter of switching the URI's used in the example.  The rdf:about on the skos:Concept becomes http://zbw.eu/stw/descriptor/19289-4 and the rdf:about on the rdf:Description becomes the URI for the bibliographic resource and the rdf:resource on the dct:subject becomes http://zbw.eu/stw/descriptor/19289-4.  Sorry for the confusion.
	
	        
	
	        Andy.
	
	        
	
	        From: Neubert Joachim [mailto:J.Neubert@zbw.eu]
	        Sent: Thursday, January 22, 2009 11:04 AM
	        To: Houghton,Andrew; public-esw-thes@w3.org
	        Subject: AW: substitute for skos:isSubjectOf
	
	        
	
	        Hi Andy,
	
	        
	
	        I'm not sure if I understood exactly what you mean. In my example, http://zbw.eu/stw/descriptor/19289-4 is the URI of the skos:Concept. I do not see how I could express an inverse relation to dc:subject by means of dcterms:relation. As rdfs:seeAlso, dcterms:relation in itself appears to me too general to serve as an substitute for skos:isSubjectOf.
	
	        
	
	        Regards, Joachim
	
	                
	
	               
	________________________________
	
	
	                Von: Houghton,Andrew [mailto:houghtoa@oclc.org]
	                Gesendet: Donnerstag, 22. Januar 2009 16:38
	                An: Neubert Joachim; public-esw-thes@w3.org
	                Betreff: RE: substitute for skos:isSubjectOf
	
	                Right, I see a few mistakes in what I did, but assuming the URI for skos:Concept is http://www.econis.eu/concept/Black+market, then change the dct:subject to http://www.econis.eu/concept/Black+market.  Now I think it says that the resource at http://zbw.eu/stw/descriptor/19289-4 has the subject Black market.  Does that help?
	
	                
	
	                Andy.
	
	                
	
	                From: Neubert Joachim [mailto:J.Neubert@zbw.eu]
	                Sent: Thursday, January 22, 2009 10:34 AM
	                To: Houghton,Andrew; public-esw-thes@w3.org
	                Subject: AW: substitute for skos:isSubjectOf
	
	                
	
	                Hi Andrew,
	
	                
	
	                dcterms:subject is defined as "The topic of the resource", and I don't want to say: The result list of the search http://www.econis.eu/...=Black+market is the subject of the skos:Concept w/ prefLabel "Black+market".
	
	                
	
	                Regards, Joachim
	
	                        
	
	                       
	________________________________
	
	
	                        Von: Houghton,Andrew [mailto:houghtoa@oclc.org]
	                        Gesendet: Donnerstag, 22. Januar 2009 16:22
	                        An: public-esw-thes@w3.org
	                        Betreff: RE: substitute for skos:isSubjectOf
	
	                        Why couldn't you do something like:
	
	                        
	
	                        <?xml version="1.0"?>
	
	                        <rdf:RDF
	
	                          xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
	
	                          xmlns:dct="http://purl.org/dc/terms/"
	
	                          xmlns:skos="http://www.w3.org/2008/05/skos#"
	
	                        >
	
	                          <skos:Concept rdf:about="http://www.w3.org/">
	
	                            <skos:prefLabel>Black market</skos:prefLabel>
	
	                            <dct:relation>
	
	                              <rdf:Description rdf:about="http://zbw.eu/stw/descriptor/19289-4">
	
	                                <dct:subject rdf:resource="http://www.econis/...=Black+market" />
	
	                              </rdf:Description>
	
	                            </dct:relation>
	
	                          </skos:Concept>
	
	                        </rdf:RDF>
	
	                         
	
	                        
	
	                        
	
	                        From: public-esw-thes-request@w3.org [mailto:public-esw-thes-request@w3.org] On Behalf Of Neubert Joachim
	                        Sent: Thursday, January 22, 2009 9:57 AM
	                        To: public-esw-thes@w3.org
	                        Subject: substitute for skos:isSubjectOf
	
	                        
	
	                        The SKOS Primer recommends using dc:subject for indexing purposes. For the inverse relation - this concept "is subject of" or "indexes" that resource - it gives no recommendation. The discussion about indexing properties in SKOS (commendably summarized in http://www.w3.org/2006/07/SWD/wiki/SkosDesign/Indexing) also paid no attention to the now vanished skos:isSubjectOf.
	
	                        
	
	                        But it's definitively missing. My use case is this:
	
	                        
	
	                        On the upcoming RDFa-enriched web pages for the Standard Thesaurus Economics (maintained by the German National Library of Economics, ZBW), we will include links to library resources. This links trigger a search for the concept at hand in the subject index of the library database - e.g.
	
	                        http://www.econis.eu/DB=1/LNG=EN/CMD?ACT=SRCHM&IKT3=46&TRM3=Black+market searches for the concept http://zbw.eu/stw/descriptor/19289-4 with the prefLabel "Black market" and returns a result page with further links to books, articles and so on (not RDFa-enriched up to now, but this could change). To enhance the Web of Linked Data, I want to express this relationship in RDFa also. A triple
	
	                        
	
	                        http://zbw.eu/stw/descriptor/19289-4 <http://zbw.eu/stw/descriptor/19289-4>  skos:isSubjectOf http://www.econis.eu/...=Black+market
	
	                        
	
	                        would have been perfect. (Of cause, the inverse relation can be expressed easily by dc:subject, but that puts the descriptor in the object position.)
	
	                        
	
	                        I understand that the missing relation may be, strictly spoken, not part of the KOS (but an application of the KOS to resources) and therefore may be outside the scope of SKOS. But nevertheless a substitute is required.
	
	                        
	
	                        It would be easy to define some custom property, e.g. zbw:indexes, with skos:Concept as domain and rdf:resource as range. But since I feel that this may be a requirement not only by our site, there should be a more common, standardized way.
	
	                        
	
	                        I did some research on this, but was out of luck:
	
	                        
	
	                        - dc:subject lacks an inverseProperty
	
	                        - sioc:topic dito
	
	                        - dcterms:references/dcterms:isReferencedBy seems to be aimed at citations and alike
	
	                        - ore:describes/ore:isDescribedBy is too restricted in Domain/Range (ore:ResourceMap/ore:Aggregation)
	
	                        - rdfs:seeAlso is too general
	
	                        - frbr:isSubjectOf could be fine if domain and range are sufficiently general, but I couldn't figure out the status of this one (it is described as a skos:Concept in http://sandbox.metadataregistry.org/concept/show/id/923.html, but is not part of http://purl.org/vocab/frbr/core or http://purl.org/vocab/frbr/extended)
	
	                        
	
	                        I'm convinced that terminologies - expressed in SKOS - could perfectly serve as hubs in a Web of Linked Data. To this end, it would be highly beneficial to figure out and recommend a uniform way to link from skos:Concepts to arbitrary other resources. Can we do this?
	
	                        
	
	                        Kind regards, Joachim
	
	                        
	
	
	
Received on Friday, 23 January 2009 14:40:21 UTC

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