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Re: Problem with property path test case pp15

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Tue, 19 Apr 2011 08:55:13 +0100
Message-ID: <4DAD3FE1.4090502@epimorphics.com>
To: Olivier Corby <olivier.corby@inria.fr>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>


On 19/04/11 08:39, Olivier Corby wrote:
>>> In addition, what is the rationale for matching "IRIs explicitly given
>>> as endpoints of the path pattern" ?
>>
>> Originally from:
>>
>> ?x rdf:type/rdfs:subClassOf* <T> .
>> ---------
>> project ?x
>> ?x rdf:type ?v . ?v rdfs:subClassOf* <T> .
>>
>> so if there is no
>>
>> <a> rdfs:subClassOf* <T> .
>>
>> this works when done in either order:
>>
>> ?x rdf:type ?v . ?v rdfs:subClassOf* <T> .
>> or
>> ?v rdfs:subClassOf* <T> . ?x rdf:type ?v .
>
> In the example above, ?x rdf:type <T> must be in the graph and hence <T>
> is in the graph.
> But my question was about URI that are *not present* in the graph (like
> in pp15) : what is the design rationale for this exception to SPARQL
> graph pattern matching ?

In a string regexp:

"a*" matches "bbbbbb"

The analogy is not perfect but it is illustrative.

The subproperty case:

?p rdfs:subPropertyOf <P>
?s ?p ?o .

means <P> is not usually a subject or object in the graph.

	Andy
Received on Tuesday, 19 April 2011 07:55:52 GMT

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