Re: Exactly one element in a RDFS class

As such I will just write:

:MyClass my:cardinality 1 .


:MyClass my:isSingleton true .

(I think, the first of these two signleton definitions is better, as it is more extensible.)

Now detecting which classes are intended to be singletons for my purposes is trivial.

17.11.2014, 17:49, "Peter F. Patel-Schneider" <>:
> Writing a SPARQL construct query to determine which classes are de facto
> singletons is not possible, as far as I can tell. šThere are very many ways
> for an OWL class to be a de facto singleton beside being equivalent to a
> singleton set. šFor 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. šFor 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:
>> šI think you need to preprocess your data with a sparql construct query to find
>> šout what classes are de facto singletons, and to assign those classes a
>> špunning type such as :Singleton. After that, you can use Ada.
>> šBest
>> šAldo
>> šOn Monday, November 17, 2014, Peter F. Patel-Schneider <
>> š<>> wrote:
>> šššššI'm having a very hard time coming up with any overlap between this
>> šššššdiscussion and anything that might happen in the RDF data shapes working
>> šššššgroup. šThe working group is about detecting explicit information in RDF
>> šššššdocuments---this discussion is about how to create singleton classes, and
>> šššššmaybe how to detect such singleton classes in an RDF encoding.
>> šššššThat said, SPARQL is used in several of the technologies being
>> šššššinvestigated by the working group and it is probably possible to write a
>> šššššSPARQL query to detect a singleton class in the RDF encoding of OWL, but
>> šššššthis doesn't provide any true commonality.
>> šššššpeter
>> šššššOn 11/17/2014 01:50 AM, Phil Archer wrote:
>> šššššššššThis sort of debate is exactly the kind of thing that is behind the newly
>> šššššššššformed RDF Data Shapes working group. Its charter includes pointers to
>> ššššššššša bunch
>> šššššššššof existing work in this area that may be useful.
>> šššššššššSee
>> ššššššššš<>
>> šššššššššCheers
>> šššššššššPhil.
>> šššššššššOn 16/11/2014 23:03, Pavel Klinov wrote:
>> šššššššššššššThere's no simpler encoding. Nominals is the only feature in OWL 2
>> šššššššššššššwhich lets you say that a class has a single instance. And it has a
>> šššššššššššššunique serialization in RDF.
>> šššššššššššššI don't think querying for this particular syntactic construct is
>> šššššššššššššcomplex.
>> šššššššššššššHowever, writing RDF queries for OWL ontologies serialized in RDF (be
>> šššššššššššššthat SPARQL or other RDF graph matching language) is usually not a
>> šššššššššššššgreat idea. You'll often have to deal with specifics of the RDF
>> šššššššššššššserialization which is complex for many OWL constructs (see [1])
>> šššššššššššššCheers,
>> šššššššššššššPavel
>> ššššššššššššš[1]
>> ššššššššššššš<>
>> šššššššššššššOn Sun, Nov 16, 2014 at 11:35 PM, Victor Porton <>
>> šššššššššššššwrote:
>> šššššššššššššššššYour solution has the same problem as Patrick Logan's one.
>> ššššššššššššššššš(See my previous
>> šššššššššššššššššemail.) In fact your solution is the same as Patrick Logan's one.
>> ššššššššššššššššš17.11.2014, 00:28, "Pavel Klinov" <>:
>> šššššššššššššššššššššSorry, my previous email got sent too soon.
>> šššššššššššššššššššššHere's the link to the right place in the OWL 2 spec:
>> ššššššššššššššššššššš
>> ššššššššššššššššššššš<>
>> šššššššššššššššššššššCheers,
>> šššššššššššššššššššššPavel
>> šššššššššššššššššššššOn Sun, Nov 16, 2014 at 10:52 PM, Victor Porton
>> ššššššššššššššššššššš<> wrote:
>> ššššššššššššššššššššššššššššIs there any advise on how to code in RDFS or OWL
>> šššššššššššššššššššššššššthe following statement?
>> šššššššššššššššššššššššššššš"The class X has exactly one element."
>> šššššššššššššššššššššššššššš--
>> ššššššššššššššššššššššššššššVictor Porton -
>> ššššššššššššššššš--
>> šššššššššššššššššVictor Porton -

Victor Porton -

Received on Monday, 17 November 2014 15:52:30 UTC