Re: shapes as classes

I believe that the working group is obligated to use class in the way that it 
is defined in RDF.  If shapes/constraints are indeed always RDF classes, then 
the working group can say so.  If RDF classes are indeed always 
shapes/constraints, then the working group can say so.  If there is no 
inclusion relationship, however, the working group is obligated not to make 
statements that imply that there is an inclusion relationship.

peter


On 12/14/2014 08:15 PM, Holger Knublauch wrote:
> I find it easier to explain what I mean via specific examples (in RDF). From
> that perspective, a Shape can be regarded as a Resource that has constraints
> attached to it. In OWL such shapes often correspond to anonymous classes, used
> via owl:allValuesFrom and owl:someValuesFrom.
>
> # Every Person must have a social security number
> ex:Person
>      a owl:Class ;
>      rdfs:subClassOf [
>          a owl:Restriction ;
>          owl:onProperty ex:ssn ;
>          owl:cardinality 1 ;
>      ] ...
>
> However, the shapes such as the owl:Restriction above are technically still
> owl:Classes, only that are used in a specific context only, and not of
> interest to the outside world (therefore blank nodes). Furthermore, such blank
> nodes are usually not instantiated via rdf:type, but are only used to declare
> additional conditions that certain values must fulfill. Following this, a
> Class is a Shape that can be instantiated directly, usually via rdf:type.
>
> Technically, the terms Class and Shape are very similar to me. To avoid
> confusion, we could try to use the term Class only, assuming that a class
> describes a set of instances with shared characteristics.
>
> Holger
>
>
> On 12/13/2014 10:09, Holger Knublauch wrote:
>> Please feel free to edit the page and come up with a better wording. It was
>> just a proposal. We can fight about words forever, without making progress.
>>
>> Holger
>>
>>
>> On 12/13/14, 9:35 AM, Peter F. Patel-Schneider wrote:
>>> So RDF classes are not shapes, and neither are OWL classes.
>>>
>>> But why then does
>>> https://www.w3.org/2014/data-shapes/wiki/Resource_Shape_Association say
>>> that classes are shapes?
>>>
>>> peter
>>>
>>>
>>> On 12/12/2014 03:11 PM, Holger Knublauch wrote:
>>>> This depends on how you define the term Shape. To me, a Shape is a group of
>>>> connected constraints, so if a class has no constraints then it is not really
>>>> a Shape (unless you include the unconstrained Shape to be a Shape too).
>>>>
>>>> Holger
>>>>
>>>>
>>>> On 12/13/14, 9:02 AM, Peter F. Patel-Schneider wrote:
>>>>> But are all classes shapes?
>>>>>
>>>>> peter
>>>>>
>>>>>
>>>>> On 12/12/2014 02:52 PM, Holger Knublauch wrote:
>>>>>>
>>>>>> On 12/13/14, 3:40 AM, Peter F. Patel-Schneider wrote:
>>>>>>> If "Shape" is more general than "Class", shouldn't all classes be shapes?
>>>>>>
>>>>>> Some classes are just named entities without any constraints.
>>>>>>
>>>>>> Holger
>>>>>>
>>>>>>
>>>>
>>>>
>>
>
>

Received on Tuesday, 16 December 2014 18:36:02 UTC