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Hi Jan, Simon, This is indeed a problem from the perspective of dctersm:type, and the practioners who want to want to retained 'OWL-DL'ness. From the SKOS perspective, there's indeed nothing formally wrong with having something declared (or infered) both as a skos:Concept and an rdfs:Class. Next to the pointers already exchanged I could also refer to http://www.w3.org/TR/skos-primer/#secskosowl http://www.sciencedirect.com/science/article/pii/S1570826813000176 (5th page) So the questions are whether your case really needs DL-compatibility (many cases just don't need this). And of course remains the one, whether dcterms:type has the best axiomatization possible. I agree with you that the current axioms makes it too close to rdf:type. Plus, reacting to your sentence below: > The other problem is that as a result of this, people are hesitant to use skos:Concept as the value of this property. > I believe this has not prevented people to create statements using dcterms:type with simple strings (literals), which is even worse from a formal perspective. (note: I personally don't care so much about creating such statements, especially after I'm told to use the stricter dcterms: namespace rather than the good old flexible dc11: namespace) Best, Antoine On 8/13/15 6:41 AM, Simon J D Cox wrote: > Hi Jan - > > Ok - I think I understand a bit better. The issue is not so much the SKOS meta-modelling capability, but the formal definition of dcterms:type. As you point out, if > > dcterms:type rdfs:range rdfs:Class . > > then it is rather too similar to rdf:type! > > In the RDF universe, rdf:type is a special predicate, being the only one that is routinely used to cross meta-levels, relating instances to types (classes). The formal semantics of dcterms:type appears to duplicate rdf:type, and precludes the use of a skos:Concept as its value because of the risk of breaking DL semantics. > > Simon > > ------------------------------ > > Date: Wed, 12 Aug 2015 06:05:21 +0000 > From: Jan Voskuil <[log in to unmask]> > Subject: Re: DC-ARCHITECTURE Digest - 10 Aug 2015 to 11 Aug 2015 (#2015-26) > > Hello Simon, > The problem you are referring to is related to but slightly different from the dcterms:type-issue. > I agree that a given skos:Concept often "refers to" or "is about" something that may be thought of as a class or set. > > Note that "refers to" here is used not in the rdf-semantics sense of the word. The notion of aboutness causes instances of skos:Concept to function as a kind of metamodeling-vocabulary. > > In my current project we use instances of skos:Concept to make "first class modeling concepts" in our vocabularies easily accessible and findable. To do this, we use foaf:focus to relate the concept in the thesaurus to the class, property or individual in our ontology. Example: > > ex:OrganisationConcept a skos:Concept ; > foaf:focus rov:RegisteredOrganisation. > > Interesting literature on this is [1], [2] and [3]. > > Note, however, that in the above example individuals and classes are strictly separated. The construction satisfies strict DL-constraints. One problem with dcterms:type is that it introduces punning and is (to some undefined degree) synonymous to rdf:type, independently of the metamodeling-features of SKOS. The other problem is that as a result of this, people are hesitant to use skos:Concept as the value of this property. -Jan > > [1] http://xmlns.com/foaf/spec/#term_focus > [2] “Getty Vocabularies: Linked Open Data Semantic Representation”, chapter 3 “Concept vs Thing Duality”, http://vocab.getty.edu/doc/#Concept_vs_Thing_Duality. > [3] Pete Johnston, “Things & their conceptualisations: SKOS, foaf:focus & modelling choices”, http://efoundations.typepad.com/efoundations/2011/09/things-their-conceptualisations-skos-foaffocus-modelling-choices.html > > > ________________________________________ > Van: DCMI Architecture Forum <[log in to unmask]> namens Simon J D Cox <[log in to unmask]> > Verzonden: woensdag 12 augustus 2015 01:23 > Aan: [log in to unmask] > Onderwerp: Re: DC-ARCHITECTURE Digest - 10 Aug 2015 to 11 Aug 2015 (#2015-26) > > Dear Jan - > This is actually a well-known problem/feature (depending on your pov) in SKOS. > SKOS Concepts are often 'classes' in the generic sense, but the SKOS RDF vocabulary makes them instances. > SKOS is really a bridging vocabulary to help move traditional 'vocabularies' into RDF, but stops short of modelling them fully as classes. > Your reference to 'punning' is on point. Don't expect DL compliance. > > Simon Cox > > > Simon J D Cox > Research Scientist > Environmental Information Infrastructures Land and Water CSIRO > > E [log in to unmask] T +61 3 9545 2365 M +61 403 302 672 Until 2015-09-06: > 37 Graham Road, Highett, Vic 3190 > PO Box 56, Highett, Vic 3190 > From 2015-09-07: > Bayview Avenue, Clayton, Vic 3168 > Private Bag 10, Clayton South, Vic 3169 people.csiro.au/C/S/Simon-Cox > orcid.org/0000-0002-3884-3420 > researchgate.net/profile/Simon_Cox3 > > PLEASE NOTE > The information contained in this email may be confidential or privileged. Any unauthorised use or disclosure is prohibited. If you have received this email in error, please delete it immediately and notify the sender by return email. Thank you. To the extent permitted by law, CSIRO does not represent, warrant and/or guarantee that the integrity of this communication has been maintained or that the communication is free of errors, virus, interception or interference. > > Please consider the environment before printing this email. > > > ----------------------------- > > Date: Tue, 11 Aug 2015 16:55:54 +0100 > From: Jan Voskuil <[log in to unmask]> > Subject: dcterms:type and SKOS (retried) > > Dear all, > In recent work I have struck on a problematic interaction between SKOS and DC. These standards should strengthen each other. Using SKOS to publish value lists and then to use the skos:Concepts therein as the value of, for instance, dcterms:subject, offers significant benefits. However, there is a problem with dcterms:type, because it is declared with rdfs:Class as its range. This complicates the use of instances of skos:Concept as its value. >