- From: Alistair Miles <a.j.miles@rl.ac.uk>
- Date: Mon, 27 Nov 2006 17:09:38 +0000
- To: Bernard Vatant <bernard.vatant@mondeca.com>
- CC: public-esw-thes@w3.org
Bernard Vatant wrote: > Hi Alistair > > Happy to see you have a look at this. Mieux vaut tard que jamais :-) > > Since the thread has been quite long, do you want me to try and sum up > the issue? I would be very grateful if you could. In no more than three sentences? ;) Thanks, Alistair. > > Cheers > > Bernard > > Alistair Miles a écrit : >> >> Hi Stuart, >> >> Quick comment without having read the subsequent thread in detail ... >> >> I think you have revealed a potential inconsistency in the design of >> SKOS. Certainly worthy of an item in the issues list - I'll do that >> when I get a chance. >> >> Cheers, >> >> Alistair. >> >> Williams, Stuart (HP Labs, Bristol) wrote: >>> Hello, >>> >>> Firstly I am new to SKOS, so apologies if this has come up before. >>> >>> The SKOS guide (as indicated in this thread) discourages the use of >>> owl:sameAs to establish equivalence relations between skos:Concepts >>> because: >>> >>> <http://www.w3.org/TR/swbp-skos-core-guide/#secidentity> >>> "The property owl:sameAs should not be used to express the fact that >>> two conceptual resources (i.e. resources of type skos:Concept) share >>> the same meaning. The property owl:sameAs implies that two resources >>> are identical in every way (they are in fact the same resource). >>> Although two conceptual resources may have the same meaning, they may >>> have different owners, different labels, different documentation, >>> different history, and of course a different future." >>> >>> However, the use of skos:subjectIndicator, defined inverse >>> functional, is described in: >>> >>> <http://www.w3.org/TR/swbp-skos-core-guide/#secpsi> >>> "The property skos:subjectIndicator allows you to assert a link >>> between a concept and a human-readable document that provides a >>> complete, definitive description of that concept. >>> ... >>> The skos:subjectIndicator property is an >>> owl:InverseFunctionalProperty, which means that if any two nodes in >>> an RDF graph have the same value for this property, then they are the >>> same resource [OWL]. Therefore you can use the skos:subjectIndicator >>> property to indirectly identify a concept by reference to the URI of >>> the document that is the published subject indicator for that concept." >>> >>> So... if the same skos:subjectIndicator is asserted for two (or more) >>> skos:Concepts then it can be inferred that they are the same >>> skos:Concept which seems to be at odds with the desire *not* to >>> establish such equivalences as expressed in the narrative above >>> discouraging the use of owl:sameAs. >>> >>> Is there a reason why concept equivalences established via the >>> skos:subjectIndicator are "good" and equivalencies established via >>> owl:sameAs are bad? >>> >>> Thanks, >>> >>> Stuart Williams >>> -- >>> HP Labs, Bristol. >>> >>>> Hi, >>>> >>>> There is a confusion of different things here. >>>> >>>> 1- skos:Concept is a class. >>>> 2- instances of skos:Concept are called "concepts" in the SKOS >>>> documents. >>>> >>>> 3- mapping of skos:Concept to another class can be done with >>>> owl:equivalentClass >>>> 4- mapping of instances of skos:Concept to other skos:Concept >>>> instances (from other vocabularies) can be done with owl:sameAs >>>> 5- mapping of instances of skos:Concept to other instances (from >>>> other vocabularies) can also be done with the SKOS mapping >>>> properties, e.g. exactMatch [1] >>>> >>>> Now the confusion is about which kind of mapping (3-5) is meant. The >>>> "Concept Identity and Mapping" section [2] states that mapping type >>>> 4 should not be used, instead type 5 is better. This is because the >>>> former states that they are the same *in every respect*, while the >>>> latter only states that their extensions are the same (set of docs >>>> indexed with one concept is also properly indexed with the other). >>>> If you use the former you also merge their metadata, e.g. date of >>>> creation and scheme they belong to. They become indistinguishable. >>>> The latter keeps them distinguishable. >>>> >>>> The text mentioned does not refer to type 3 at all. This mapping >>>> would be required if someone is not using the SKOS schema for a >>>> vocabulary, but something similar. Then a mapping >>>> >>>> skos:Concept owl:equivalentClass my:Concept >>>> >>>> can be used to make all instances of my:Concept also skos:Concepts, >>>> so they can be manipulated by software that understands SKOS. >>>> >>>> Hope this helps, >>>> Mark. >>>> >>>> [1]http://www.w3.org/2004/02/skos/mapping/spec/#exactMatch >>>> [2]http://www.w3.org/TR/2005/WD-swbp-skos-core-guide-20051102/#secidentity >>>> >>>> >>>> Nabonita Guha wrote: >>>>> */Bernard Vatant <bernard.vatant@mondeca.com>/* wrote: >>>>> >>>>> >A skos:Concept is not a class, and the domain of >>>>> owl:equivalentClass is >>>>> >owl:Class >>>>> >>>>> Whereas in SKOS Core guide >>>>> (http://www.w3.org/TR/2005/WD-swbp-skos-core-guide-20051102/#secconcept), >>>>> skos:Concept has been described as a class. If it's not a Class >>>>> then what it can be considered as? >>>>> >>>>> Best, >>>>> >>>>> Nabonita Guha >>>>> >>>>> Senior Research Fellow >>>>> Documentation Research & Training Centre >>>>> Indian Statistical Institute >>>>> Bangalore INDIA >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> Hi Andrew >>>>> > The SKOS guide [1], in the "Concept Identity and Mapping" >>>>> section, states that owl:sameAs *should not* be used to indicate >>>>> that two concepts share the same meaning. It gives some >>>>> rationale in >>>>> the section for this. Looking at the OWL guide [2], in the "4.1. >>>>> Equivalence between Classes and Properties" section, I'm wondering >>>>> whether one can use owl:equivalentClass to indicate that two >>>>> concepts share the same meaning. If there is a reason why >>>>> owl:equivalentClass can/cannot be used for this, should it also be >>>>> mentioned in "Concept Identity and Mapping" section? >>>>> > >>>>> Yes, there is a good reason. >>>>> A skos:Concept is not a class, and the domain of >>>>> owl:equivalentClass is >>>>> owl:Class >>>>> >>>>> Cheers >>>>> >>>>> Bernard >>>>> >>>>> > >>>>> > Thanks, Andy. >>>>> > >>>>> > [1] >>>>> > [2] >>>>> > >>>>> > >>>>> > >>>>> >>>>> -- >>>>> *Bernard Vatant >>>>> *Knowledge Engineering >>>>> ---------------------------------------------------- >>>>> *Mondeca** >>>>> *3, cité Nollez 75018 Paris France >>>>> Web: www.mondeca.com >>>>> ---------------------------------------------------- >>>>> Tel: +33 (0) 871 488 459 >>>>> Mail: bernard.vatant@mondeca.com >>>>> Blog: Leçons de Choses >>>>> >>>>> >>>>> >>>>> ------------------------------------------------------------------------ >>>>> >>>>> Want to start your own business? Learn how on Yahoo! Small >>>>> Business. >>>>> <http://us.rd.yahoo.com/evt=41244/*http://smallbusiness.yahoo.com/r-index> >>>>> >>>> -- >>>> Mark F.J. van Assem - Vrije Universiteit Amsterdam >>>> markREMOVE@cs.vu.nl - http://www.cs.vu.nl/~mark >>> >> > -- Alistair Miles Research Associate CCLRC - Rutherford Appleton Laboratory Building R1 Room 1.60 Fermi Avenue Chilton Didcot Oxfordshire OX11 0QX United Kingdom Web: http://purl.org/net/aliman Email: a.j.miles@rl.ac.uk Tel: +44 (0)1235 445440
Received on Monday, 27 November 2006 17:10:27 UTC