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Re: shapes-ISSUE-209 (What is a shape?): What is a shape [SHACL Spec]

From: Holger Knublauch <holger@topquadrant.com>
Date: Thu, 24 Nov 2016 10:48:49 +1000
To: public-data-shapes-wg@w3.org
Message-ID: <2278de09-9d98-c93f-c011-1b2306c2097e@topquadrant.com>
The current definition in 2.1 reads

Ashapecan be anode <#dfn-node>in ashapes graph <#dfn-shapes-graph>that 
is aSHACL instance <#dfn-shacl-instance>of|sh:Shape|; or it can be a 
node so that theexpected type <#dfn-expected-type>of the node 
is|sh:Shape|, or a node that has avalue <#dfn-values>for atarget 
<#dfn-target>property such as|sh:targetClass|in theshapes graph 
<#dfn-shapes-graph>.

These are all (3) ways of how shapes are identified. I have just added 
some precision based on the newly introduced term shape-expecting 
constraint parameters, and explicitly enumerated the target properties. 
The definition now reads

Ashapecan be anode <#dfn-node>in ashapes graph <#dfn-shapes-graph>. A 
node is a shape if and only if it fulfills either of the following 
conditions in the shapes graph:

  * the node is aSHACL instance <#dfn-shacl-instance>of|sh:Shape|
  * the node has theexpected type <#dfn-expected-type>|sh:Shape|, which
    is the case if it is used as a value ofshape-expecting constraint
    parameters <#dfn-shape-expecting-constraint-parameters>such
    as|sh:shape|(in the case of the list-valued
    parameters|sh:and|,|sh:or|and|sh:partition|it must be a member of
    the corresponding lists)
  * the node has avalue <#dfn-values>for any of thetarget
    <#dfn-target>properties|sh:targetClass|,|sh:targetNode|,|sh:targetObjectsOf|,|sh:targetSubjectsOf|and|sh:target|


Change:

https://github.com/w3c/data-shapes/commit/bec7b6852529acc80954dbc38cf4e435861238a2

I'd appreciate if WG members could double check this definition. 
Meanwhile I have turned the change above into a PROPOSAL for a future 
meeting:

https://www.w3.org/2014/data-shapes/wiki/Proposals#ISSUE-209:_What_is_a_shape

Thanks,
Holger


On 24/11/2016 9:49, Irene Polikoff wrote:
> I believe the question is "How do I know that a node is a shape?". The 
> spec says that it is "typically" a SHACL instance of sh:Shape. This is 
> one way, but not the definitive way (because of "typically") to 
> determine that something is a shape.
>
> What are other ways? E.g., any subject of a triple with one of the 
> SHACL target or constraint predicates is a shape.
>
> On Sun, Nov 20, 2016 at 3:58 PM, RDF Data Shapes Working Group Issue 
> Tracker <sysbot+tracker@w3.org <mailto:sysbot+tracker@w3.org>> wrote:
>
>     shapes-ISSUE-209 (What is a shape?): What is a shape [SHACL Spec]
>
>     http://www.w3.org/2014/data-shapes/track/issues/209
>     <http://www.w3.org/2014/data-shapes/track/issues/209>
>
>     Raised by: Karen Coyle
>     On product: SHACL Spec
>
>     Peter's mail:
>     https://lists.w3.org/Archives/Public/public-rdf-shapes/2016Oct/0029.html
>     <https://lists.w3.org/Archives/Public/public-rdf-shapes/2016Oct/0029.html>
>
>     "Just what are shapes?
>
>     The terminology section says:
>
>     "Shape
>     A shape is a node in a shapes graph that is typically a SHACL
>     instance of
>     sh:Shape. A shape provides a collection of targets, filters,
>     constraints and
>     parameters of constraint components that specify how a data graph is
>     validated against the shape. Shapes can also provide non-validating
>     information, such as labels and comments."
>
>     Section 2 says:
>
>     "Shapes define constraints that a set of focus nodes can be validated
>     against."
>
>     This doesn't, however, provide guidance in determining what the
>     shapes in a
>     shapes graph are."
>
>     (more in the email)
>
>
>
>
>
>
Received on Thursday, 24 November 2016 00:49:26 UTC

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