W3C home > Mailing lists > Public > public-data-shapes-wg@w3.org > May 2016

Re: Simplification of scopes section (see also ISSUE-148)

From: Karen Coyle <kcoyle@kcoyle.net>
Date: Sun, 15 May 2016 07:42:26 -0700
To: public-data-shapes-wg <public-data-shapes-wg@w3.org>
Message-ID: <57388AD2.6030707@kcoyle.net>


On 5/14/16 1:08 PM, Peter F. Patel-Schneider wrote:
> One problem with having all shapes initiate validation is that embedded shapes
> would as well.
>
> So in
>
> ex:s1 rdf:type sh:Shape ;
>    sh:scopeClass ex:Person ;
>    sh:property [ sh:predicate ex:dependent ;
>                  sh:valueShape [ a sh:Shape ;
>                                  sh:property [ sh:predicate ex:SSN ;
>                                                sh:minCount 1 ] ] ] .
>
> the scope of the embedded shape would be all nodes in the data graph,
> resulting in validation reports for any node that does not have a value for
> ex:SSN.

I thought that filter shapes would be used if further refinement of the 
scope is needed. This appears to be using a shape for that purpose (and 
I don't recall this being mentioned before). Even with a defined scope 
it isn't clear to me what the scope in the embedded shape would act on 
as its initial input, since the spec says that a shapes graph is 
compared to a data graph, but the result of scoping \= a new data graph. 
? Anyway, is embedding shapes allowed? If so, what are the rules for how 
that is implemented?

kc

>
> If all shapes are to have scopes then there are ways around this problem.  One
> would be that shapes are not embedded in other shapes.  Instead there would be
> a new kind of SHACL thing that is used when the current effect of embedding
> shapes in shapes is desired.
>
> peter
>
>
> On 05/14/2016 01:00 PM, Karen Coyle wrote:
>> That may be what one interprets from the current spec, but it doesn't preclude
>> us from considering the logic that I proposed, which is that a shape's scope
>> is the data graph unless further scoping is defined. Obviously, this makes
>> more sense to me than requiring a scope. Also, we do not at this point have a
>> scope defined that would represent the entire data graph. How would I work
>> with a set of triples with no defined classes and of which I could not know a
>> priori the identity of a node?
>>
>> I know this seems outlandish, but I'm thinking of the possibility of operating
>> on received data that you need to investigate to see what state it is in. One
>> role for validation is to analyze data sources that don't present with
>> sufficient rigor or with pre-defined documentation. Some validation programs
>> are going to have to work with unknowns and with bad data. This is one of the
>> functions of validation in the massively shared cultural heritage community.
>> One needs to be able to get some information out of data graphs that don't
>> conform to expectations. It seems to me that being able to do some checking on
>> the data graph as a whole could have value. (But I'll also check with my peeps
>> about this and get back to this list.)
>>
>> kc
>>
>>
>>
>> On 5/14/16 12:23 PM, Irene Polikoff wrote:
>>> Yes, this was my interpretation as well, but I wanted to confirm.
>>>
>>>
>>> Irene
>>>
>>>
>>>
>>>
>>>
>>> On 5/14/16, 3:01 PM, "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
>>> wrote:
>>>
>>>> If a shape has no scopes then
>>>> no validation is initiated by that shape.
>>>
>>>
>>>
>>
>

-- 
Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet/+1-510-984-3600
Received on Sunday, 15 May 2016 14:42:52 UTC

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