Re: SHACL dependence on EXISTS

> On 2016-07-06, at 18:22, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
> 
> SHACL, the in-progress result of the W3C Data Shapes Working Group with
> Editors' draft at http://w3c.github.io/data-shapes/shacl/, depends on EXISTS
> in several ways.
> 
> The most prominent is that SHACL has basic graph patterns inside EXISTS that
> need to work correctly if a filter variable is mapped to a blank node.  For
> example,
>  SELECT $this ($this AS ?subject) $predicate (?value AS ?object)
>  WHERE {
>  $this $predicate ?value .
>  FILTER NOT EXISTS { ?value rdf:type/rdfs:subClassOf* $class } .
>  }

this reads as if it corresponds to "problem 3” from the "catalog of problems with EXISTS”.
is that true?

> […]  However, SHACL doesn't here
> dictate how EXISTS should work, SHACL just needs EXISTS to work.  […]

is it possible to characterize, as examples, any other cases where a particular behaviour was expected, but not observed.

> 
> The most important in my view, however, is that SHACL centrally uses
> pre-binding, i.e., evaluating SPARQL queries with variables "pre-bound" to
> values.  In the above query the variables using $ are all pre-bound. 

to my understanding, as this group has been described by andy seaborne, that topic is not in its scope.

> Begin forwarded message:
> 
> From: Andy Seaborne <andy@apache.org>
> Subject: Re: Improving EXISTS
> Date: 2016-06-29 17:12:51 CEST
> To: public-rdf-tests@w3.org
> Resent-From: public-rdf-tests@w3.org
> 
> On 26/06/16 13:07, james anderson wrote:
>> 
>> - request parameters are a de facto requirement, as they were
>> established by sesame and now users expect them.
>> if there is to be an effort to ratify a standard behaviour, that
>> deserves a group of its own, independent of any concern for shapes
>> and/or exists.
> 
> Certainly useful and important.
> 
> My preference is for a quite tightly focused CG mainly so it knows when it's finished and we can see if the approach of using CG's is viable. The biggest factor I see is lack of people's time.
> 
> There is nothing to preclude another one.  Nor of making a proposal to public-sparql-dev@w3. There choices for protocol-parametrized queries such as it just one set of name/values injected or a table of?

best regards, from berlin,




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