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RE: shapes and classes: different

From: Irene Polikoff <irene@topquadrant.com>
Date: Mon, 26 Jan 2015 14:59:36 -0500
To: "'Peter F. Patel-Schneider'" <pfpschneider@gmail.com>, "'Jerven Tjalling Bolleman'" <jerven.bolleman@isb-sib.ch>
Cc: "'RDF Data Shapes Working Group'" <public-data-shapes-wg@w3.org>
Message-ID: <19e201d039a2$9d71caf0$d85560d0$@topquadrant.com>
This doesn't answer my question as to how practically these are different.

In the shape validation, we are saying that the validation will occur if something explicitly indicates that it should. For example, there is a type triple to Square or there is another triple that says "validate" this resource as if it was a Square.

Given that the only information available is

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

ex:whatami will not be validated against the Square definition. If the type triple was present (or there was some other statement that says validate ex:whatami against Square), then it would be validated. How the type triple gets to be there is outside the scope.


-----Original Message-----
From: Peter F. Patel-Schneider [mailto:pfpschneider@gmail.com] 
Sent: Monday, January 26, 2015 2:25 PM
To: Irene Polikoff; 'Jerven Tjalling Bolleman'
Cc: 'RDF Data Shapes Working Group'
Subject: Re: shapes and classes: different

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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 20:00:08 UTC

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