- From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
- Date: Mon, 17 Nov 2014 08:37:55 -0800
- To: Aldo Gangemi <aldo.gangemi@istc.cnr.it>
- CC: Phil Archer <phil@philarcher.org>, Pavel Klinov <pavel.klinov@uni-ulm.de>, Victor Porton <porton@narod.ru>, SW-forum Web <semantic-web@w3.org>
So I guess then there were two different situations being answered: 1/ Stating in RDFS or OWL that a class has to have exactly one instance. 2/ Stating that a class has exactly one explicitly stated instance. To many of us, the initial question could only be interpreted in the first way, and this cannot be done in RDFS, which left only OWL. peter On 11/17/2014 08:23 AM, Aldo Gangemi wrote: > 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 16:38:25 UTC