- From: Antoine Isaac <aisaac@few.vu.nl>
- Date: Sat, 05 Dec 2009 11:49:01 +0100
- To: Richard Cyganiak <richard.cyganiak@deri.org>
- CC: Peter DeVries <pete.devries@gmail.com>, public-lod@w3.org, dmozzherin@gmail.com
Hi Richard, > So, can an rdfs:Class also be used as a skos:Concept, or vice versa? Yes. > OWL DL folks will obviously not like this, but that's not my problem. > > A problem might be this: If there is a skos:Concept, and we use it as a > class, what exactly are the instances of that class? Having this: > > foo:Cougar a skos:Concept; skos:prefLabel "Cougar". > > And then doing this: > > bar:Bob a foo:Cougar . > > Then Bob could be an animal, or Bob could be some sort of document, > because the foo:Cougar concept may have been a "container" for documents > rather than animals. So the "bar:Bob a foo:Cougar" triple really just > tells us that bar:Bob is somehow related to or about cougars, but not > that Bob is an animal of the species Cougar. This problem could be > solved by saying that "foo:Cougar rdfs:subClassOf ex:Animal". So the > problem can be worked around. But it still shows that using concepts as > classes is tricky business. I never pretended that was easy, just that there were fewer problems ;-) However, I would in general expect that the link between a document and its subject should be represented by a dedicated property that is not rdf:type [1]. If people generally adopted this pattern, there would be less chance of someone's using the cougar concept as the class of documents about cougars, which I expect is the most likely confusion. But of course you can never remove all danger. When you start using a concept as a class, I guess it would be good practice to add some documentation (e.g. an rdfs:comment on the class) to clarify your intention. As you say in the following, one can expect less issues for the other direction. All (RDFS/OWL) ontologies can be regarded as knowledge organization systems, but KOSs are generally not trivially mapped into ontologies. > The other way round -- using classes as concepts -- seems safer. I find > it hard to find a practical problem with this. Both for classes and for > concepts there are custom properties for indicating equivalence -- > owl:equivalentClass and the different skos:match properties -- so one > can steer clear of owl:sameAs and avoid most of the usual coreference > problems. Yes! Antoine [1] http://www.w3.org/TR/skos-primer/#secindexing > > > On 3 Dec 2009, at 18:58, Antoine Isaac wrote: >>>> And in fact, while I understand that it is not very intuitive to >>>> have Bob the cougar as a skos:Concept (even though it is technically >>>> allowed), I see less problems for dealing this way with the class of >>>> cougars... >>> Mentioning that you see less problems without going into any detail >>> is not exactly useful. I see more problems. >> >> Yes, I should have been clearer. >> >> In fact the most important argument (as I understand it from the >> discussion you started at [1]) against considering a given entity as a >> skos:Concept is that this entity may not have been designed as part as >> a knowledge organization endeavour. It is for example rather >> far-stretched to say that a person like Michelle Obama was conceived >> as part of a knowledge organization system. >> My point is that this is less problematic for classes, as these are >> items of a knowledge organization system from the start. They are also >> "taxonomist business objects", aren't they? So we could easily treat >> them as skos:Concepts. >> We have in fact touched this aspect in some parts of the SKOS >> documentation [2,3,4]. I'd be very interested to know whether you >> think this is wrong view! >> >> Best, >> >> Antoine >> >> [1] http://lists.w3.org/Archives/Public/public-esw-thes/2009Nov/0000.html >> [2] http://www.w3.org/TR/2009/NOTE-skos-primer-20090818/#secskosowl >> [3] http://www.w3.org/TR/skos-reference/#L896 >> [4] http://www.w3.org/TR/skos-reference/#L1170 >> >> >>>> >>>> Best, >>>> >>>> Antoine >>>> >>>>> 2. I'm not sure if it's wise to use the same URI for the Cougar >>>>> "concept" and the Cougar "class". I don't think that this "punning" >>>>> is against any spec, but it will cause endless head-scratching >>>>> among potential users of your data. It would be more >>>>> straightforward to mint a separate URI for the class, and relating >>>>> it 1:1 to the species concept using an appropriate property >>>>> (there's probably one in UMBEL; if not, mint your own -- maybe >>>>> "speciesClass"). Since you own the URI space anyway, minting new >>>>> URIs would be cheap. >>>>> This kind of punning between concepts, things and classes is an >>>>> interesting issue, and I'm afraid that it's not yet well >>>>> understood. Avoiding it puts you on the safe side. >>>>> That being said, can you talk a bit about your motivation for >>>>> wanting to re-use the same URI? >>>>> Best, >>>>> Richard >>>>>> >>>>>> This should work with OWL2 but I don't know how well it will work >>>>>> with the >>>>>> LOD. >>>>>> >>>>>> Also I created a VERY preliminary OWL document that would contain >>>>>> a much >>>>>> more complete representation of the species. >>>>>> >>>>>> My thoughts are that these OWL documents would be used to help >>>>>> determine >>>>>> what specimens are instances of what species concept. >>>>>> The goal would be to provide an OWL document for those who need a >>>>>> more >>>>>> complete description of what we mean by the URI, while >>>>>> also providing a much lighter RDF representation that could be >>>>>> used for >>>>>> concept mapping etc. >>>>>> >>>>>> However, I don't know if I am going about this in the right way. >>>>>> >>>>>> Below are my VERY preliminary examples of what these OWL documents >>>>>> might >>>>>> look like. >>>>>> >>>>>> The example has some attributes that I thought should be included >>>>>> in a >>>>>> species document, but it does not have everything that would like to >>>>>> eventually include. >>>>>> >>>>>> http://rdf.taxonconcept.org/owlses/v6n7p/2009-12-01.owl >>>>>> >>>>>> Doc's at http://rdf.taxonconcept.org/owlses/v6n7p/owl_doc/index.html >>>>>> >>>>>> The common classes etc, would eventually be moved to a separate >>>>>> ontology >>>>>> that would be imported into each individual species ontology. >>>>>> >>>>>> And these ontologies will need to be fixed so that they work >>>>>> together, I >>>>>> don't think they do right now. >>>>>> >>>>>> Thanks in Advance, :-) >>>>>> >>>>>> - Pete >>>>>> ---------------------------------------------------------------- >>>>>> Pete DeVries >>>>>> Department of Entomology >>>>>> University of Wisconsin - Madison >>>>>> 445 Russell Laboratories >>>>>> 1630 Linden Drive >>>>>> Madison, WI 53706 >>>>>> GeoSpecies Knowledge Base >>>>>> About the GeoSpecies Knowledge Base >>>>>> ------------------------------------------------------------ >>>> >> >> > > >
Received on Saturday, 5 December 2009 10:49:39 UTC