- From: Miles, AJ (Alistair) <A.J.Miles@rl.ac.uk>
- Date: Fri, 1 Oct 2004 13:40:24 +0100
- To: "'public-esw-thes@w3.org'" <public-esw-thes@w3.org>
I think what I meant was ... If we have two resources: ex:resourceA a skos:Concept; skos:prefLabel 'Alistair Miles'; skos:scopeNote 'My mate Al.' . ex:resourceB a foaf:Person; foaf:name 'Alistair Miles'; foaf:mbox <mailto:a.j.miles@rl.ac.uk> . ... the burining questions are: Are these two resources fundamentally different in nature, or not? Are these two resources at different levels of abstraction, or not? My point in the last email [1] was that, it *does not* seem reasonable to allow for example: ex:resourceC a skos:Concept; skos:prefLabel 'Alistair Miles'; skos:scopeNote 'My mate Al.'; a foaf:Person; foaf:name 'Alistair Miles'; foaf:mbox <mailto:a.j.miles@rl.ac.uk> . ... intuitively because properties like 'skos:scopeNote' seem appropriate to describe an abstract concept, but not to describe a person. I.e. in logic speak the classes skos:Concept and foaf:Person should be disjoint. What Dave said in an earlier email (I think) was that I should not think of ex:resourceB as an actual person, but as an abstract entity, with the same metaphysical status as ex:resourceA (i.e. they are both abstractions). But intuitively I do think of ex:resourceB as an actual person (should I change that?), and that feeling is the basis for my assertion above. And even if I do accept they are both abstractions, one *feels* to me more abstract than the other. Are we getting closer or farther away? Al. [1] http://lists.w3.org/Archives/Public/public-esw-thes/2004Oct/0000.html --- Alistair Miles Research Associate 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 Tel: +44 (0)1235 445440 > -----Original Message----- > From: public-esw-thes-request@w3.org > [mailto:public-esw-thes-request@w3.org]On Behalf Of NJ > Rogers, Learning > and Research Technology > Sent: 01 October 2004 12:36 > To: Miles, AJ (Alistair); 'public-esw-thes@w3.org' > Subject: RE: [Proposal][SKOS-Core] skos:denotes > > > > Ok, so you're talking about the class/instance issue, right? > > You're saying that OWL classes and foaf classes for example > can be used in > the range of the rdf type property. So that a resource may be > of *type* > person. > And you're saying that naturally skos Concept *instances* (e.g. > myskos:Person - a skos concept that represents the concept of > a Person > (?!)) can*not* be used in the range of the rdf type property. > > So you're saying, for these cases, that in order to indicate e.g. a > foaf:Person (class) has some association with > e.g.myskos:Person (instance) > we need a skos:denotes property in SKOS Core. > > I get this logic. But I still don't get why this is machinery is so > important. When do we want to query RDF data in a way such > that we need > skos:denotes? It must be blindingly obvious, but please point > it out to me, > gimme an example!! > > /me thinks further: is it that we might want to phrase RDF > queries such > that we effectively ask "this foaf:Person class, what concept does it > relate to?..." > > Thanks > Nikki > > > > --On Friday, October 01, 2004 11:57:06 +0100 "Miles, AJ (Alistair) " > <A.J.Miles@rl.ac.uk> wrote: > > > > > How about this for an argument as to why resources of type > skos:Concept > > are at a different level of abstraction to, say for > example, resources of > > type foaf:Person ... > > > > You would not say that a 'scopeNote' or a 'definition' is a > property of a > > person. > > > > However, you might reasonably say that an 'email address' > or 'date of > > birth' is a property of a person. > > > > Al. > > > > --- > > Alistair Miles > > Research Associate > > 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 > > Tel: +44 (0)1235 445440 > > > > > > > >> -----Original Message----- > >> From: public-esw-thes-request@w3.org > >> [mailto:public-esw-thes-request@w3.org]On Behalf Of Dave Reynolds > >> Sent: 30 September 2004 18:38 > >> To: Matthews, BM (Brian) > >> Cc: 'public-esw-thes@w3.org' > >> Subject: Re: [Proposal][SKOS-Core] skos:denotes > >> > >> > >> > >> Matthews, BM (Brian) wrote: > >> > >> > As I interpret this, this gives the best semantics I know of for > >> > Thesaurus concepts - a concept's denotation is "the set of > >> resources > >> > which are classified under that concept" (my words). > This is quite > >> > different from the intended use in Ontologies, where > instances are > >> > "supposed" to stand for "real-world" things (with suitable > >> philosophical > >> > quotation marks). > >> > >> I agree with that summary of the semantics of Thesaurus > >> concepts but I'm > >> not so sure ontologies are that different. Sure in > >> philosophical terms > >> ontologies are more than that, as you say, but in practical > >> RDFS and OWL > >> terms a class is just a set of instances and an instance is just a > >> "resource". It so happens that OWL gives you some machinery > >> for identifying > >> the class of a resource by its properties, and RDFS gives you > >> less, but the > >> difference between those and your semantics for Thesaurus > >> concepts is just > >> a matter of expressivity rather than of fundamental nature. > >> > >> Personally I find this article nicely captures this view that > >> they are just > >> a continuum with different expressivity and degree of formality: > >> http://www.metamodel.com/article.php?story=20030115211223271 > >> > >> > So I think that the word "denotes" to connect a > >> thesaurus-theoretic and > >> > a ontology-theoretic point of view is dangerous - as in logic > >> > and mathematics this usually signifies semantics - we are > >> not (should > >> > not) be saying that the class provides a semantics for > the concept. > >> > >> Agreed. > >> > >> > An alternative term then? skos:classifierFor is perhaps > >> most precise, > >> > though a bit awkward. But I prefer it to the > alternatives we have > >> > seen so far which imply some kind of semantic relationship. > >> > >> To me that also implies a semantic relationship but maybe > >> that's just me. > >> > >> > Nikki says: > >> > > >> >> Or is this debate really about the fact that we want to > stick some > >> >> machinery capable of SKOS<->OWL stuff in SKOS-Core right > >> now, so that > >> >> SKOS-Core stands in its own right allowing us to tackle > >> SKOS-Mapping > >> >> separately? > >> > > >> > > >> > As far as I see - yes! The use of this property is to do > >> the modelling > >> > task of relating SKOS and OWL - and SKOS-mapping should > be separate. > >> > >> To me there's no particular difference between saying that two SKOS > >> Concepts are trying to model the same "real world" thing and > >> saying that a > >> SKOS Concept and an OWL Class are trying to model the same > >> "real world" > >> thing. So I'm with Nikki, it seems odd putting it in the core > >> rather than > >> in mapping. > >> > >> > To turn to the specifics of the proposal (to start a new > >> controversy), > >> > does it make sense (particularly when taking a point of view that > >> > we are providing a classifier for an RDF resource) for > this property > >> > to be a functional property? This would mean if two > >> resources have the > >> > same classifier, they can be identified. This may not > make sense. > >> > >> My vote would be "no". > >> > >> For example, you might have a SKOS Thesaurus concept > >> "my:Person" an RDF > >> Class foaf:Person and an RDF Class drc:Person. They are all > >> trying to model > >> the same real world notion but in different ways (e.g. > >> drc:Person might > >> have cardinality restrictions on properties that foaf:Person > >> has nothing to > >> do with). As I understand it, the point of this property is > >> to be able to > >> say "my:Person and foaf:Person are both attempts to model the > >> same thing" > >> without carrying any semantics such as cardinality restrictions. > >> > >> It would be reasonable to also want to say "my:Person and > >> drc:Person are > >> both attempts to model the same thing" without that implying that > >> drc:Person = foaf:Person (with all that would entail from > the formal > >> semantics of the foaf and drc schemas). > >> > >> Cheers, > >> Dave > >> > >> > > > > > > ---------------------- > NJ Rogers, Technical Researcher > (Semantic Web Applications Developer) > Institute for Learning and Research Technology (ILRT) > Email:nikki.rogers@bristol.ac.uk > Tel: +44(0)117 9287096 (Direct) > Tel: +44(0)117 9287193 (Office) >
Received on Friday, 1 October 2004 12:40:57 UTC