Re: New Terminology Section

On 5/6/16 9:14 AM, Peter F. Patel-Schneider wrote:
> I think that instead of reiterating descriptions from RDF 1.1 Concepts and
> Abstract Syntax, and having errors in at least one of the descriptions, it
> would be better to just defer to that document.

In particular, the definition of class is problematic:

Class
A class is a IRI or blank node representing a set of nodes. SHACL makes 
no assumption whether a class has certain values for the rdf:type property.

The RDF Schema document says:

"Resources may be divided into groups called classes. The members of a 
class are known as instances of the class. Classes are themselves 
resources. They are often identified by IRIs and may be described using 
RDF properties. The rdf:type property may be used to state that a 
resource is an instance of a class."

... the "class has certain values" doesn't make sense. And I have 
commented before about the use of "representing" - things either "are" 
or "are not" but there isn't representation happening, IMO.

The big question, though, in my mind, is whether the use of classes in 
SHACL follows the definition in RDFS.

In terms of the data graph, the RDFS concept of class is used only in 
the sense that nodes can be identified as a triple with a predicate 
"rdf:type" and some designated value.

In the shapes graph, I'm not at all clear on how classes are being used. 
There are a lot of declared classes that appear to have no functionality 
within the standard. I'm going to open up an issue so we can try to 
clarify what classes in SHACL are - that may help us with finding wording.

>
> I think that it is a bad idea to redefine terms from RDF and RDFS.  Like it or
> not, some readers of SHACL documents will use the RDF and RDFS definitions of
> terms like subclass and superclass when reading SHACL documents even if these
> terms are redefined in the SHACL documents.

I agree with this. It means carefully rewording a fair amount of the 
SHACL document, but it is necessary for clarity.

kc

>
> peter
>
>
>
>
> On 05/05/2016 11:49 PM, Holger Knublauch wrote:
>> As suggested today, I have added a Terminology section to the very start of
>> the document:
>>
>>      http://w3c.github.io/data-shapes/shacl/#terminology
>>
>> The primary goal of this section is to provide reasonably formal definitions
>> of the key concepts so that we have this out of the way, and so that later
>> passages of the document can hyperlink to them. I created a HTML coding
>> convention that makes it easy to maintain such links, allowing us to switch
>> terms (such as replacing "instance" with "SHACL instance") if needed. Such
>> internal links to the definitions show up with a light grey underline,
>> distinguishable from other hyperlinks.
>>
>> The secondary goal of this section is to serve as a quick overview for the
>> casual reader. But my understanding is that this spec is not the right place
>> to serve as a tutorial for beginners, and someone should create a Primer with
>> a different audience in mind.
>>
>> The third goal of this section is for us to have a compact space to
>> collaborate on proper definitions that inform the rest of the document. I
>> would appreciate feedback/iterations on these definitions so that we reach a
>> fixpoint. We could then align the rest of the document once we are happy.
>>
>> Thanks
>> Holger
>>
>>
>
>

-- 
Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet/+1-510-984-3600

Received on Friday, 6 May 2016 17:34:28 UTC