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Re: shapes-ISSUE-134 (knowing inverse): does SHACL syntax distinguish inverse property constraints [SHACL Spec]

From: Karen Coyle <kcoyle@kcoyle.net>
Date: Wed, 6 Apr 2016 21:43:35 -0700
To: public-data-shapes-wg@w3.org
Message-ID: <5705E577.7010805@kcoyle.net>
Thanks, Holger. But can you say exactly which classes will be defined as 
disjoint from each other? I'm still finding this rather vague. Or maybe 
it's in the issue somewhere?

kc

On 4/6/16 7:27 PM, Holger Knublauch wrote:
> Karen,
>
> I don't think you need to be concerned. This is merely about corner
> cases such as
>
> ex:MyShape
>      a sh:Shape ;
>      sh:property ex:c ;
>      sh:inverseProperty ex:c .
>
> ex:c a sh:PropertyConstraint ;
>      sh:predicate ....
>
> i.e. a constraint node is shared as both sh:property and
> sh:inverseProperty. I don't think anybody would practically do this, but
> we need to exclude that possibility to help the engine decide which
> SPARQL to run.
>
> It does not make the use of, say, sh:minCount and sh:class disjoint with
> each other.
>
> HTH
> Holger
>
>
> On 7/04/2016 12:22, Karen Coyle wrote:
>> All WHAT disjoint? All constraints? That not only makes me nervous
>> about unintended consequences, but in addition since we've rejected
>> inferencing, I'm not sure what it does. If nothing else, pairwise
>> disjoint rules on every possible combination of constraints could be
>> burdensome if your software is expected to enforce that. And I'd like
>> a run-through of the constraints to make sure this doesn't trip us up
>> somewhere down the line. In general, my preference is to avoid
>> declaring disjoint classes or properties except when absolutely
>> necessary.
>>
>> Could you give an example of the case that brought this up, and see if
>> it generalizes to other constraint classes?
>>
>> kc
>>
>> On 4/6/16 12:57 AM, Holger Knublauch wrote:
>>> Yeah, why not. I just made them all disjoint. This is a rather
>>> theoretical corner case anyway, so being conservative here will make our
>>> lives easier:
>>>
>>> The
>>> classes|sh:NodeConstraint|,|sh:PropertyConstraint|and|sh:InversePropertyConstraint|are
>>>
>>> pairwise disjoint, i.e. it is illegal to have shape definitions that use
>>> nodes that are instances of two or more of these classes - either
>>> explicitly stated via|rdf:type|or implicitly via theirdefault value
>>> type.
>>>
>>> Thanks,
>>> Holger
>>>
>>>
>>> On 6/04/2016 17:42, Dimitris Kontokostas wrote:
>>>>
>>>> On Wed, Apr 6, 2016 at 10:08 AM, Holger Knublauch
>>>> <<mailto:holger@topquadrant.com>holger@topquadrant.com> wrote:
>>>>
>>>>     On 11/03/2016 15:57, Holger Knublauch wrote:
>>>>>     Ok, we can leave this ticket open here as a reminder that this
>>>>>     needs to be clarified. Like the other unwritten details about
>>>>>     sh:property vs sh:inverseProperty vs sh:constraint, this will be
>>>>>     cleaned up once we have resolved the general metamodel discussion.
>>>>
>>>>     I believe this ISSUE-134 can be closed now: Section 2.3 now
>>>>     includes a paragraph:
>>>>
>>>>     The
>>>> classes|sh:PropertyConstraint|and|sh:InversePropertyConstraint|are
>>>>     disjoint, i.e. it is illegal to have shape definitions that use
>>>>     nodes that are instances of both classes - either explicitly
>>>>     stated via|rdf:type|or implicitly via theirdefault value type.
>>>>
>>>>
>>>> Can we say that all constraint types are pairwise disjoint?
>>>> we can get in similar cases when someone uses sh:NodeConstraint
>>>> and sh:InversePropertyConstraint
>>>> this means that constraint IRIs can be reused but only with same
>>>> constraint types
>>>> Dimitris
>>>>
>>>>
>>>>
>>>> --
>>>> Dimitris Kontokostas
>>>> Department of Computer Science, University of Leipzig & DBpedia
>>>> Association
>>>> Projects: <http://dbpedia.org>http://dbpedia.org,
>>>> http://rdfunit.aksw.org,
>>>> http://<http://aligned-project.eu/>http://aligned-project.eu
>>>> Homepage:<http://aksw.org/DimitrisKontokostas>http://aksw.org/DimitrisKontokostas
>>>>
>>>> Research Group: AKSW/KILT http://aksw.org/Groups/KILT
>>>>
>>>
>>
>
>
>

-- 
Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet/+1-510-984-3600
Received on Thursday, 7 April 2016 04:43:13 UTC

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