RE: Blank nodes for concepts.

That's my reading of (b)

Al:
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.


> -----Original Message-----
> From: Charles McCathieNevile [mailto:charles@w3.org] 
> Sent: 06 February 2004 01:05
> To: Steve Cayzer
> Cc: Miles, AJ (Alistair) ; public-esw-thes@w3.org
> Subject: Re: Blank nodes for concepts.
> 
> 
> 
> 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
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Received on Friday, 6 February 2004 03:48:12 UTC