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Re: Handling multiple rdfs:ranges

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 24 Feb 2016 23:18:43 -0600
Cc: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>, semantic-web@w3.org
Message-Id: <EBA3BA9A-3E7E-4050-ADE9-849311627AA7@ihmc.us>
To: Reto Gmür <reto@wymiwyg.com>

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. 

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 Thursday, 25 February 2016 05:19:13 UTC

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