- From: Holger Knublauch <holger@topquadrant.com>
- Date: Thu, 13 Oct 2016 15:41:59 +1000
- To: public-rdf-shapes@w3.org
I have added a note to
https://www.w3.org/2014/data-shapes/track/issues/170
to link to this email thread. ISSUE-170 seems to cover the same topic
and will be handled by the WG in due course.
Holger
On 13/10/2016 13:04, Peter F. Patel-Schneider wrote:
> Because of the problems with EXISTS in SPARQL many ASK-defined constraint
> components have unusual meanings according to their SPARQL definition.
>
> For example, the data graph
>
> ex:i1 rdf:type ex:C , D ;
> ex:p _:b1 .
>
> validates against the shapes graph
>
> s:s1 rdf:type sh:Shape ;
> sh:targetClass ex:C ;
> sh:property [ sh:predicate ex:p ;
> sh:class ex:D ] .
>
> This is probably not intended behaviour.
>
>
> Note that this is separate from the continuing problems with pre-binding.
>
>
>
> SPARQL definition for sh:class
>
> ASK {
> $value rdf:type/rdfs:subClassOf* $class .
> }
>
> Resultant query
>
> SELECT DISTINCT $this ?value
> WHERE {
> $this $PATH ?value .
> FILTER NOT EXISTS { $value rdf:type/rdfs:subClassOf* $class . }
> }
>
>
> When validating ex:i1 the first BGP should (if pre-binding were fixed)
> result in a single mapping
> { (this, ex:i1), (value, _:b1) }
> EXISTS substitution then results in
> BGP(_:b1 rdf:type/rdfs:subClassOf* $class . )
> which produces (again if pre-binding were fixed) a single mapping that maps
> _:b1 to ex:i1
> so the FILTER is false.
>
> So the SELECT returns an empty result and so the data graph validates
> against the shapes graph.f
>
>
> Peter F. Patel-Schneider
> Nuance Communications
>
Received on Thursday, 13 October 2016 05:42:30 UTC