- From: Aldo Gangemi <aldo.gangemi@istc.cnr.it>
- Date: Mon, 17 Nov 2014 17:23:24 +0100
- To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
- Cc: Aldo Gangemi <aldo.gangemi@istc.cnr.it>, Phil Archer <phil@philarcher.org>, Pavel Klinov <pavel.klinov@uni-ulm.de>, Victor Porton <porton@narod.ru>, SW-forum Web <semantic-web@w3.org>
I was suggesting a pragmatic answer, which requires a quite trivial query, since it only acts on the closed world of existing triples and named classes of a dataset. Of course, if we generalize the problem to any possible class, including entailment regimes, skolems, class constructions, then you’re right. > On Nov 17, 2014, at 4:49:13 PM , Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote: > > Writing a SPARQL construct query to determine which classes are de facto singletons is not possible, as far as I can tell. There are very many ways for an OWL class to be a de facto singleton beside being equivalent to a singleton set. For example, the class could be equivalent to the intersection of two sets that have single member in common. > > It is also possible for non-class axioms to produce de facto singleton OWL classes. For example what might look to be a doubleton could be turned into a singleton by a sameAs. > > In general, SPARQL is not powerful enough to analyze OWL classes. > > peter > > > On 11/17/2014 07:32 AM, Aldo Gangemi wrote: >> I think you need to preprocess your data with a sparql construct query to find >> out what classes are de facto singletons, and to assign those classes a >> punning type such as :Singleton. After that, you can use Ada. >> Best >> Aldo >> >> On Monday, November 17, 2014, Peter F. Patel-Schneider <pfpschneider@gmail.com >> <mailto:pfpschneider@gmail.com>> wrote: >> >> I'm having a very hard time coming up with any overlap between this >> discussion and anything that might happen in the RDF data shapes working >> group. The working group is about detecting explicit information in RDF >> documents---this discussion is about how to create singleton classes, and >> maybe how to detect such singleton classes in an RDF encoding. >> >> That said, SPARQL is used in several of the technologies being >> investigated by the working group and it is probably possible to write a >> SPARQL query to detect a singleton class in the RDF encoding of OWL, but >> this doesn't provide any true commonality. >> >> peter >> >> >> On 11/17/2014 01:50 AM, Phil Archer wrote: >> >> This sort of debate is exactly the kind of thing that is behind the newly >> formed RDF Data Shapes working group. Its charter includes pointers to >> a bunch >> of existing work in this area that may be useful. >> >> See http://www.w3.org/2014/data-__shapes/ >> <http://www.w3.org/2014/data-shapes/> >> >> Cheers >> >> Phil. >> >> >> On 16/11/2014 23:03, Pavel Klinov wrote: >> >> There's no simpler encoding. Nominals is the only feature in OWL 2 >> which lets you say that a class has a single instance. And it has a >> unique serialization in RDF. >> >> I don't think querying for this particular syntactic construct is >> complex. >> >> However, writing RDF queries for OWL ontologies serialized in RDF (be >> that SPARQL or other RDF graph matching language) is usually not a >> great idea. You'll often have to deal with specifics of the RDF >> serialization which is complex for many OWL constructs (see [1]) >> >> Cheers, >> Pavel >> >> [1] http://www.w3.org/TR/owl2-__mapping-to-rdf/ >> <http://www.w3.org/TR/owl2-mapping-to-rdf/> >> >> On Sun, Nov 16, 2014 at 11:35 PM, Victor Porton <porton@narod.ru> >> wrote: >> >> Your solution has the same problem as Patrick Logan's one. >> (See my previous >> email.) In fact your solution is the same as Patrick Logan's one. >> >> 17.11.2014, 00:28, "Pavel Klinov" <pavel.klinov@uni-ulm.de>: >> >> Sorry, my previous email got sent too soon. >> >> Here's the link to the right place in the OWL 2 spec: >> >> http://www.w3.org/TR/owl2-__syntax/#Enumeration_of___Individuals >> <http://www.w3.org/TR/owl2-syntax/#Enumeration_of_Individuals> >> >> Cheers, >> Pavel >> >> On Sun, Nov 16, 2014 at 10:52 PM, Victor Porton >> <porton@narod.ru> wrote: >> >> Is there any advise on how to code in RDFS or OWL >> the following statement? >> >> "The class X has exactly one element." >> >> -- >> Victor Porton - http://portonvictor.org >> >> >> -- >> Victor Porton - http://portonvictor.org >> >> >> >> >>
Received on Monday, 17 November 2014 16:23:55 UTC