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Re: Handling multiple rdfs:ranges

From: Pat Hayes <phayes@ihmc.us>
Date: Tue, 1 Mar 2016 22:45:09 -0600
Cc: David Booth <david@dbooth.org>, semantic-web@w3.org
Message-Id: <5B9018F8-6A2B-45F1-8C2D-DB2C83A9CF1F@ihmc.us>
To: Reto Gmür <reto@wymiwyg.com>

On Feb 29, 2016, at 2:50 AM, Reto Gmür <reto@wymiwyg.com> wrote:

> On Mon, Feb 29, 2016, at 03:04, David Booth wrote:
>> On 02/26/2016 06:04 AM, Reto Gmür wrote:
>>> Sure, still I think that schema:rangeIncludes is not meaningless (as it
>>> restricts the rdfs:range statements that are possible) and that
>> 
>> Under the standard open world assumption (OWA) I do not think it is 
>> correct to say schema:rangeIncludes *restricts* anything.  Bear in mind 
>> that given the statement:
>> 
>>   :p schema:rangeIncludes :Cat .
>> 
>> one could always add an arbitrary additional class to the property's 
>> "expected type(s)" by adding another statement like:
>> 
>>  :p schema:rangeIncludes :Dog .
>> 
>> Therefore, the original statement cannot be *restricting* anything 
>> (under the OWA).
> 
> I did not say that it restricts the possible values of the properties,
> but I'm saying that it restricts the possible rdfs:range statements that
> are possible without creating a contradiction.
> 
>> 
>> Personally, I think a reasonable way to interpret its meaning is that it 
>> says 'there exists an individual :d such that :d rdf:type :Dog'.
>> 
>>> it has
>>> some pragmatic usefulness such as when building editors that suggest
>>> values for a specific property.
>> 
>> Agreed.  And it's also useful if you're doing closed world reasoning.
> 
> Well, even if you're closing the world I'm not sure you can do reasoning
> about the instance data based on this property.
> 
> I claim that for something to be expected it must be possible, based on
> this one can create a contradiction with statements of necessity
> expressed with rdfs:range.

Nothing in the RDFS namespace can express anything about necessity. RDFS is not a modal logic. 

Pat Hayes

> 
> However, I don't think that only what is expected is possible. So even
> if we know that only :Cat and :Dog are expected the unexpected :Mouse is
> still possible.
> 
> Reto
> 
> 

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Received on Wednesday, 2 March 2016 04:45:43 UTC

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