Re: on divergence between textual and SPARQL definitions

sh:in is another example

Any place where a variable binding that could be to a blank node is carried
into an EXISTS and the variable is used in a BGP is a problem.  But all uses
of EXISTS have to be carefully examined as there are other problems with EXISTS.

peter




From: Holger Knublauch <holger@topquadrant.com>
Date: Sat, 10 Dec 2016 11:02:54 +1000
To: "public-rdf-sha." <public-rdf-shapes@w3.org>
Message-ID: <3cd4b9fb-fcfe-6ee7-c314-e3c6dc64c99b@topquadrant.com>

Peter, you stated there are several places but only enumerated one
(sh:class). Are the others also only about the EXISTS issue?

Holger


On 9/12/2016 12:46, Peter F. Patel-Schneider wrote:
> There are several places where the textual definition of validation differs
> from the SPARQL definition.
>
>
> Consider, for example the shapes graph
>
> se:s1 rdf:type sh:Shape ;
>   sh:targetNode ex:n ;
>   sh:property [ sh:predicate ex:p ;
>                 sh:class ex:c ] .
>
> and the data graph
>
> ex:n ex:p ex:m .
> ex:m rdf:type ex:c ;
>    ex:p ex:l .
>
>
> According to the textual definition of sh:ClassConstraintComponent this data
> graph conforms to this shapes graph as no validation result is produced for
> ex:n because its sole value for ex:p is a SHACL instance of ex:c in the data
> graph.
>
>
> The SPARQL definition here uses the following SPARQL query
>
> SELECT DISTINCT $this ?value
> WHERE {
>    $this ex:p ?value .
>    FILTER NOT EXISTS
>      { $value rdf:type/rdfs:subClassOf* $class . }
>    }
>
> with this pre-bound to ex:n and class pre-bound to ex:c.
>
> According to the SHACL document
> evaluating this SPARQL query will produce a non-empty solution sequence,
> namely
>    { { (this, ex:m), (value,ex:l) } }
> because
>    $this ex:p ?value .
> will produce the set of solutions
>    { { (this, ex:n), (value,ex:m) } ,
>      { (this, ex:m), (value,ex:l) } }
>
> Therefore according to the SPARQL definition of sh:ClassConstraintComponent
> this data graph does not conform to this shapes graph.
>
>
>>>>>>>>>>>>>>>>>>> ISSUE<<<<<<<<<<<<<<<<<<<<<<<<
> The textual and SPARQL definitions conflict in several places.  One or the
> other needs to be fixed or dropped.
>>>>>>>>>>>>>>>>>>> ISSUE<<<<<<<<<<<<<<<<<<<<<<<<
>
>
> Peter F. Patel-Schneider
> Nuance Communications
>

Received on Saturday, 10 December 2016 01:03:58 UTC

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