Re: Handling multiple rdfs:ranges

>From what I know, thinking about rdfs/owl:range as defining what "can be"
as range of the property is incorrect - it is defining what the range of
the property *is*, inferring a triple like: :x ex:prop1 :y . => :y rdf:type
:Dog

http://schema.org/rangeIncludes doesn't infer anything, so in case the
dataset with  :x ex:prop1 :y doesn't contain triple :y rdf:type :Cat then
there is no contradiction, and :y is a :Dog. This means defining a property
using both rdfs/owl:range http://schema.org/rangeIncludes is not advisable,
as these inconsistencies could appear. You should decide if your properties
define the types of range (using rdfs/owl:range), or you rely on them
appearing in the dataset. I would recommend to do so (including unions as
range), since it is stronger definition of the relationship, better
maintaining the intended meaning when another type information (:y rdf:type
:Cat) is added to the dataset.

(It may help to think about property defined using
http://schema.org/rangeIncludes as a class of properties, which one of the
class is being used, being determined by the external type information)

Cheers,
Jiri

On Fri, Feb 26, 2016 at 9:52 AM, Reto Gmür <reto@wymiwyg.com> wrote:

>
>
> On Thu, Feb 25, 2016, at 06:18, Pat Hayes wrote:
> >
> > On Feb 23, 2016, at 10:24 AM, Reto Gmür <reto@wymiwyg.com> wrote:
> >
> > > On Tue, Feb 23, 2016, at 17:05, Peter F. Patel-Schneider wrote:
> > >> On 02/23/2016 07:31 AM, Reto Gmür wrote:
> > >>> [...]
> > >>>
> > >>> Granted, the semantics of :rangeIncludes are very weak (under OWA)
> but
> > >>> the fact that you can create contradictions with it shows that it's
> not
> > >>> completely meaningless.
> > >>>
> > >>> ex:prop1 s:rangeIncludes :Cat .
> > >>> :Cat owl:disjointWith :Dog .
> > >>> ex:prop1 owl:range :Dog .
> > >>>
> > >>> The above graph evaluates to false in every possible world, this is
> not
> > >>> the case if you omit any of the 3 triples, this shows that
> > >>> `s:rangeIncludes` is not a meaningless decoration.
> > >>>
> > >>> Reto
> > >>
> > >> I don't think that this follows from the semantics of :rangeIncludes,
> > >> even if
> > >> you augment schema.org semantics with disjointness.
> > >
> > > In the example I also used "owl:range" to create what I thought is a
> > > contradiction.
> > >>
> > >> Perhaps one could also count the documentation of
> > >> rangeIncludes as authoritative as well.  So from
> > >> https://schema.org/rangeIncludes, rangeIncludes "[r]elates a
> property to
> > >> a
> > >> class that constitutes (one of) the expected type(s) for values of the
> > >> property" would also be part of the semantics of schema.org ranges.
> > >
> > > I considered only this definition. And based on that I still think
> there
> > > is a contradiction, if the owl:range of a property excludes :Cat (which
> > > is expressed with the statements using owl-properties), :Cat cannot at
> > > the same time "be (one of) the expected type(s) for values of the
> > > property".
> >
> > Of course it can. It only follows that the values of this particular
> > property are all in some other part of the range. According to the
> > schema.org definition of rangeIncludes, this is quite permissible.
>
> I'm not getting you.
>
> from
>
> (1) :Cat owl:disjointWith :Dog .
> (2) ex:prop1 rdfs:range :Dog .
>
> It follows that: (3) "no value of the property ex:prop1 can be an of
> type :Cat".
>
> Do we agree till here?
>
> (4) ex:prop1 s:rangeIncludes :Cat
>
> means: (5) "The class :Cat is an expected type for values of the
> property ex:prop1"
>
> Do you agree that (5) follows from (4) when using the definition from
> http://schema.org/rangeIncludes?
>
> Agreeing to both (4) and (5) boils down to:
>
>  - :cat is an impossible type for values of the property ex:prop1
>  - :cat is an expected type for values of the property ex:prop1
>
> Using the first definition of "Expect" from the oxford dictionary as
> "Regard (something) as likely to happen", I think there is a
> contradiction between asserting that something is impossible and that
> something is expected.
>
> I would really like to learn where you think my reasoning is wrong.
>
> Cheers,
> Reto
>
> > If you disagree, please suggest how to express the schema semantics as a
> > precise model-theoretic condition in such a way that it produces the
> > contradiction you expect.
> >
> > Pat Hayes
> >
> > >
> > > Reto
> > >
> > >
> > >
> >
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