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Re: Handling multiple rdfs:ranges

From: Reto Gmür <reto@wymiwyg.com>
Date: Fri, 26 Feb 2016 10:52:43 +0100
Message-Id: <1456480363.3024543.532532146.23E2B786@webmail.messagingengine.com>
To: Pat Hayes <phayes@ihmc.us>
Cc: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>, semantic-web@w3.org


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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> 
Received on Friday, 26 February 2016 09:53:08 UTC

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