- From: Charles McCathieNevile <charles@w3.org>
- Date: Thu, 5 Feb 2004 20:04:50 -0500 (EST)
- To: Steve Cayzer <steve.cayzer@hp.com>
- Cc: "Miles, AJ (Alistair) " <A.J.Miles@rl.ac.uk>, public-esw-thes@w3.org
Is there really any reason you can't have two concepts with the same prefLabel? as I understand it <Concept> <prefLabel>Bar</prefLabel> <altLabel>Baz</altLabel> </Concept> <Concept> <prefLabel>Bar</prefLabel> <altLabel>Foo</altLabel> </Concept> doesn't give you any right to infer that the two balnk nodes are the same (this would be that case if you made prefLabel map 1:1 with concepts but I think that's a bad idea anyway). Looking at user scenarios, there is an obvious cost to two concepts having the same preferred label - whenever you want to classify something by that label you need to be clear which one you mean. On the benefit side, you might well have a term that commonly refers to a couple of different concepts, and want to be easily able to look for things with the preferred Label. "accessible" is the example that springs to mind in my everyday stuff. I suspect in putting vocbularies together it's also useful. Cheers Chaals On Thu, 5 Feb 2004, Steve Cayzer wrote: > >Makes sense to me. > >Might be worth adding an explanation to one of the docos, both technical (as >below) and non technical (implication - you can't add a new concept with the >same prefLabel as another concept in the same thesaurus) > >Cheers > >Steve >----- Original Message ----- >From: "Miles, AJ (Alistair) " <A.J.Miles@rl.ac.uk> >To: <public-esw-thes@w3.org> >Sent: Thursday, February 05, 2004 6:03 PM >Subject: Blank nodes for concepts. > > >> >> Hi, >> >> A couple of people have picked up that in the examples in the documents >[1] >> [2] [3] I've encoded concepts as blank nodes, without URIs. This email >> addresses why I chose to do that. >> >> My thinking is as follows. We allow three methods for uniquely >identifying >> a concept: >> >> a. The URI for the concept. >> b. A combination of the concept's prefLabel and the URI of the >> thesaurus to which it belongs. >> c. A combination of the concept's externalID and the URI of the >> thesaurus to which it belongs. >> >> So, the following are all valid globally unique concept declarations: >> ---- >> <soks:Concept rdf:about="http://foo.com/examplethes/aconcept"/> >> ---- >> <soks:Concept> >> <soks:prefLabel>Bangers & Mash</soks:prefLabel> >> <rdfs:isDefinedBy rdf:resource="http://foo.com/examplethes"/> >> </soks:Concept> >> ---- >> <soks:Concept> >> <soks:externalID>A00456</soks:externalID> >> <rdfs:isDefinedBy rdf:resource="http://foo.com/examplethes"/> >> </soks:Concept> >> ---- >> >> I'll get to why in a minute. >> >> I also then thought, rather than giving every concept and ><rdfs:isDefinedBy> >> property to indicate membership of some conceptual scheme, why not allow >> people to subclass the <soks:Concept> class? >> >> So, for example, you could define the class: >> ---- >> <rdfs:Class rdf:about="http://foo.com/thesaurus/Concept"> >> <rdfs:subClassOf >> rdf:resource="http://www.w3c.rl.ac.uk/2003/11/21-skos-core#Concept"/> >> <rdfs:comment>This is the class of all concepts from the foo.com >> thesaurus.</rdfs:comment> >> </rdfs:Class> >> ---- >> Which would then allow globally unique concept declarations such as the >> following: >> ---- >> <foo:Concept> >> <soks:prefLabel>Bangers & Mash</soks:prefLabel> >> </foo:Concept> >> ---- >> <foo:Concept> >> <soks:externalID>A00456</soks:externalID> >> </foo:Concept> >> ---- >> >> OK, so why bother? >> >> 1. It makes for better-looking RDF encodings (this is a serious point, as >> it may help reduce the uptake hurdle - how many times have you heard >people >> groan that RDF looks like gobbledegook because of all the URIs? Also >> remember many potential users are from totally non sem-web environments, >> e.g. english heritage. RDF is a new and complicated beast to them.) >> >> 2. It may not be appropriate to give a URI to a concept that is part of >> some thesaurus that has been defined by an authority outside the semantic >> web world. So until the authority itself gives its own concepts URIs, we >> can still make statements about them using reference-by-description. >> >> On the down side ... >> >> 1. Someone has to write a bit of reasoning code to equate all blank nodes >> with the same prefLabel/rdfs:isDefinedBy property values, and run it over >> the data before publishing it. >> >> Where I fall on the matter: in the short term use URIs to identify >> concepts, so can work in a world without any reasoning required. In the >> slightly longer term look into allowing the blank-node style encodings, >and >> support the little bit of reasoning required with some code. >> >> What does everyone think? >> >> Al. >> >> >> [1] http://www.w3c.rl.ac.uk/SWAD/deliverables/8.1.html >> [2] http://www.w3c.rl.ac.uk/SWAD/deliverables/8.3.html >> [3] http://www.w3c.rl.ac.uk/SWAD/deliverables/8.4.html >> >> 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 >> >> > Charles McCathieNevile http://www.w3.org/People/Charles tel: +61 409 134 136 SWAD-E http://www.w3.org/2001/sw/Europe fax(france): +33 4 92 38 78 22 Post: 21 Mitchell street, FOOTSCRAY Vic 3011, Australia or W3C, 2004 Route des Lucioles, 06902 Sophia Antipolis Cedex, France
Received on Thursday, 5 February 2004 20:04:50 UTC