update to SHACL-SPARQL

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At the VF2F Holger pointed out a couple of problems with my proposal.

To address these, I added a requirement that constraints be binding and
modified some of the translations to make more constraints be binding.  I
also emphasized that some of the translations are inefficient and that the
translations are only a specification.



An example of a non-binding constraint is

NBC sh:shapeScope [ sh:property ex:p; sh:maxCardinality 1 ];
    sh:shape [ sh:property ex:q ; sh:minCardinality 1 ] .

Translation of this constraint into SPARQL would normally result a query
where there was nothing to make bindings to return.  The solution to the
problem in Stardog ICV is to add in a pattern like

   ?this rdf:type rdfs:Resource .

It probably is not a good idea to count on SPARQL implementations, even ones
that do RDFS inferencing, to make this kind of inference so I instead make
the requirement that SHACL conditions be binding.  I expect that nearly all
potential SHACL conditions will be binding, so I don't think that this is
much of a limitation on SHACL.




peter

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Received on Friday, 22 May 2015 14:09:48 UTC