Re: shapes-ISSUE-89 (recursion without properties): How should recursion that does not involve a property be handled? [SHACL Spec]

I have no particular problem treating non-property recursion the same as
recursion that involves properties.  I noticed that such recursion is
generally not useful, whether not it involves negation, and was wondering
whether it should be allowed.

peter


On 09/25/2015 01:25 PM, Arthur Ryman wrote:
> Peter,
> 
> I agree that ex:s1 is not useful. My initial reaction is that it would
> always be true since there is no way to generate violations. This
> interpretation is consistent with the article [1] I wrote about the
> interpretation of positive recursion using sh:valueShape (I have an
> ACTION to write a proposal) . SHACL is in effect based the presumption
> of innocence, i.e. "innocent until proven guilty".
> 
> The case of no properties may reduce to the case where properties are
> present if we imagine that all nodes have a virtual "sh:self" property
> that loops to itself (X sh:self X) and the above is like asserting
> that the property sh:self has a sh:valueShape of ex:s1.
> 
> [1] http://arxiv.org/abs/1505.04972
> 
> -- Arthur
> 
> On Tue, Sep 15, 2015 at 5:32 PM, RDF Data Shapes Working Group Issue
> Tracker <sysbot+tracker@w3.org> wrote:
>> shapes-ISSUE-89 (recursion without properties): How should recursion that does not involve a property be handled? [SHACL Spec]
>>
>> http://www.w3.org/2014/data-shapes/track/issues/89
>>
>> Raised by: Peter Patel-Schneider
>> On product: SHACL Spec
>>
>> Right now
>>
>> ex:s1 rdf:type sh:shape ;
>>       sh:constraint [ a sh:AndConstraint ;
>>                       sh:shapes ( ex:s1 ) ] .
>>
>> is valid SHACL.  However, it is not a very useful shape.
>>
>> In general, recursion between shapes where the recursion does not involve a property is not useful.
>>
>> Should such shapes be allowed in SHACL?
>>
>>
>>
>

Received on Thursday, 1 October 2015 01:34:44 UTC