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Re: Exactly one element in a RDFS class

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Mon, 17 Nov 2014 17:39:13 +0100
Message-ID: <CAK4ZFVHD9h4fBWjM14kB8gkGrP6VjVP4fms4aSQBh+qP7izamA@mail.gmail.com>
To: Victor Porton <porton@narod.ru>
Cc: SW-forum Web <semantic-web@w3.org>
Hello Victor

Not sure it's a great idea for me to answer in the face of all the OWL
gurus you have attracted :)

But ... why not an enumerated class using owl:oneOf with a single element
in the list ?

:C a owl:Class ;
    owl:equivalentClass  [ a owl:Class ; owl:oneOf (:x) ].

For me it looks like :C is thus defined by the extension {:x}.

... or do I miss something more subtle?


2014-11-17 17:23 GMT+01:00 Aldo Gangemi <aldo.gangemi@istc.cnr.it>:

> 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
> >>
> >>
> >>
> >>
> >>
>
>
>


-- 

*Bernard Vatant*
Vocabularies & Data Engineering
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Received on Monday, 17 November 2014 16:40:01 UTC

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