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Re: shapes and classes: different

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Mon, 26 Jan 2015 10:14:40 -0800
Message-ID: <54C68410.8030308@gmail.com>
To: Jerven Tjalling Bolleman <jerven.bolleman@isb-sib.ch>, RDF Data Shapes Working Group <public-data-shapes-wg@w3.org>
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It is certainly the case that OWL classes have the characteristics of both
shapes and classes because you can both assert that objects belong to OWL
classes and provide precise conditions for belonging to OWL classes.
However, it is possible to build a class system (e.g., RDFS) where classes
are not shapes and a shape system (e.g., ShExC) where shapes are not classes.

Having shapes also be classes or classes also be shapes doesn't follow from
the bare notions of shapes and classes.  It is instead a decision whose
consequences need analysis.

peter




On 01/26/2015 08:12 AM, Jerven Tjalling Bolleman wrote:
> I really can't help myself...
> 
> On 26/01/15 15:12, Peter F. Patel-Schneider wrote: The most important
> aspect of classes is that you state that objects belong to them.  If you
> don't state that objects belong to X, X is not a class.
> 
> The most important aspect of shapes is that you provide conditions
> stating precisely when an object belongs to them.   If you don't provide
> conditions stating precisely when an object belongs to X, X is not a
> shape.
> 
> Having shapes also be classes implies that you state that objects belong
> to shapes.  Having classes also be shapes implies that you provide
> recognition conditions for classes. Both situations are possible, but
> both have consequences.
>> Your word shape is my word owl:Class. Allowing class membership
>> inference from recognition conditions is as normal as class member ship
>> assertion directly in the data. But I am absolutely flabbergasted that
>> I am having this argument with one of the OWL2 editors!
> 
>> Basically I am reading your response as class membership only inferred
>> is "shape membership". Class membership asserted is not "shape
>> membership". Or paraphrased: Shapes only allows triples with the
>> shape:member predicate (IMO equivalent to rdf:type) to be inferred and
>> not asserted.
> 
> 
> 
> peter
>> 
> 
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Received on Monday, 26 January 2015 18:22:58 UTC

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