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

From: Dimitris Kontokostas <kontokostas@informatik.uni-leipzig.de>
Date: Fri, 13 May 2016 09:05:57 +0300
Message-ID: <CA+u4+a3TrKB-R7+E8zzkXW3-oPUoSuMoO+pUz850B44AZVuNmw@mail.gmail.com>
To: Holger Knublauch <holger@topquadrant.com>
Cc: public-data-shapes-wg <public-data-shapes-wg@w3.org>
No use cases from my side for sh:AllObjectsScope but I recently had a use
case with sh:AllSubjectScope (although in the end I modeled it with
sh:scopeClass )

I have been thinking a bit about these 2 cases and we could either say
something like
ex:myShape sh:allSubjectsScope "true"

or
ex:myShape sh:scope sh:AllSubjects   (and shacl somewhere defines
sh:AllSubjects rdf:type sh:AllSubjectsScope) and we can reuse that)
similar for sh:AllObjects


On Fri, May 13, 2016 at 6:37 AM, Holger Knublauch <holger@topquadrant.com>
wrote:

> On 13/05/2016 13:22, Karen Coyle wrote:
>
>>
>>
>> On 5/12/16 5:51 PM, Holger Knublauch wrote:
>>
>>> I agree the editorial arrangement of these subsections is unhelpful, and
>>> I have aligned the nesting with this commit:
>>>
>>>
>>> https://github.com/w3c/data-shapes/commit/fd044c834960c791cc1740509224057d03057567
>>>
>>>
>>> The naming and syntax issue had been raised before as
>>>
>>> https://www.w3.org/2014/data-shapes/track/issues/148
>>>
>>> I would find it very unfortunate if we switched to another syntax that
>>> hard-codes these few scope types and then requires a completely
>>> different syntax for the general scope mechanism of the extension
>>> mechanism. Such decisions drive up implementation costs significantly,
>>> and also require the reader of SHACL to look at a rather arbitrary
>>> collection of predicates.
>>>
>>
>> Yet the current design takes a very different approach between node and
>> class-based scopes, which are "hard coded", and the remaining scopes, which
>> are subclasses of sh:Shape. We have:
>>
>> ex:PersonShape
>>     a sh:Shape ;
>>     sh:scopeNode ex:Alice .
>>
>> and
>>
>> ex:PropertyScopeExampleShape
>>     a sh:Shape ;
>>     sh:scope [
>>         a sh:PropertyScope ;
>>         sh:predicate ex:knows ;
>>     ] .
>>
>> So the inconsistency is already there, to the inconvenience of the user.
>>
>
> Yes, the inconsistency is already there, but I would say for the
> convenience of the user. In particular the case of sh:scopeClass will be so
> common, that having to go through an intermediate object would be quite
> redundant. Less so for sh:scopeNode, but who can anticipate the future.
>
>
>>
>>  Also, what would be the object of ex:MyShape
>>
>>> sh:allObjectsScope triples?
>>>
>>
>> I'd like to think more about the "all objects" "all subjects" -- I'm
>> having trouble thinking of them as scopes in this same sense; I almost
>> think they'd fit into the constraints functional area. Do we have use cases
>> for those? that would help.
>>
>
> No, I don't have use cases for these. They are candidates for deletion
> IMHO, in which case we may end up with only 4 scopes to "hard-code", which
> sounds more realistic to me.
>
> Does anyone have use cases for "all subjects" and "all objects" scopes?
>
> Holger
>
>
>


-- 
Dimitris Kontokostas
Department of Computer Science, University of Leipzig & DBpedia Association
Projects: http://dbpedia.org, http://rdfunit.aksw.org,
http://aligned-project.eu
Homepage: http://aksw.org/DimitrisKontokostas
Research Group: AKSW/KILT http://aksw.org/Groups/KILT
Received on Friday, 13 May 2016 06:06:52 UTC

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