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Re: shapes and classes: different

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Mon, 26 Jan 2015 11:24:33 -0800
Message-ID: <54C69471.40008@gmail.com>
To: Irene Polikoff <irene@topquadrant.com>, 'Jerven Tjalling Bolleman' <jerven.bolleman@isb-sib.ch>
CC: 'RDF Data Shapes Working Group' <public-data-shapes-wg@w3.org>
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Consider the following RDF graph

ex:whatami rdf:type ex:rectangle .
ex:whatami ex:width "5"^^xsd:int .
ex:whatami ex:breadth "5"^^xsd:integer .

In the former situation, ex:whatami is not a square but in the second it is.

peter


On 01/26/2015 11:04 AM, Irene Polikoff wrote:
> < Saying that a square is subclass of a rectangle and that squares have
> their width and breadth equal doesn't make square a shape>
> 
> <Saying that squares are precisely those rectangles whose width and
> breadth are equal does make square a shape>
> 
> For practical purposes, what is the difference?
> 
> -----Original Message----- From: Peter F. Patel-Schneider
> [mailto:pfpschneider@gmail.com] Sent: Monday, January 26, 2015 1:21 PM 
> To: Irene Polikoff; Jerven Tjalling Bolleman Cc: RDF Data Shapes Working
> Group Subject: Re: shapes and classes: different
> 
> The defining characteristic of shapes is that they are provided with
> conditions that determine which objects belong to them.  Saying that a
> square is subclass of a rectangle and that squares have their width and
> breadth equal doesn't make square a shape even though it may be the case
> that objects belonging to square are precisely those objects that have an
> rdf:type link to  it. Saying that squares are precisely those rectangles
> whose width and breadth are equal does make square a shape as this
> provides a set of conditions that determine when an object is a square.
> 
> peter
> 
> 
> On 01/26/2015 09:24 AM, Irene Polikoff wrote:
>>> Your word shape is my word owl:Class.
> 
>> +1
> 
>> So, the simplest solution is not to have a new thing called Shape.
> 
>> Another option may be to use it as a type so that some classes can be 
>> of type Shape as well as Class.
> 
>> This seems to be unnecessary though as every class is already a shape. 
>> At minimum, even if there are no other constraints declared for a 
>> class, it says that all instances belonging to it must have a certain 
>> type triple. If there is a class :Person, then its instances must have 
>> :Person1 a ::Person triple (whether it is asserted or inferred, doesn't
>> matter). A very minimalistic data shape, but still a shape.
> 
>> Irene
> 
>> On Jan 26, 2015, at 11:12 AM, Jerven Tjalling Bolleman 
>> <jerven.bolleman@isb-sib.ch <mailto:jerven.bolleman@isb-sib.ch>>
>> 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
>>>> 
>>> 
>>> --
>>> ------------------------------------------------------------------- 
>>> Jerven Bolleman                        Jerven.Bolleman@isb-sib.ch 
>>> <mailto:Jerven.Bolleman@isb-sib.ch> SIB Swiss Institute of 
>>> Bioinformatics  Tel: +41 (0)22 379 58 85 CMU, rue Michel Servet 1 
>>> Fax: +41 (0)22 379 58 58 1211 Geneve 4, Switzerland
>>> www.isb-sib.ch <http://www.isb-sib.ch> - www.uniprot.org
>>> <http://www.uniprot.org> Follow us at https://twitter.com/#!/uniprot 
>>> -------------------------------------------------------------------
>>> 
> 
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Received on Monday, 26 January 2015 19:25:09 UTC

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