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Re: [TF-PP] Zero-length paths (ACTION-251)

From: Gregory Williams <greg@evilfunhouse.com>
Date: Fri, 4 Jun 2010 09:22:42 -0400
Cc: SPARQL Working Group WG <public-rdf-dawg@w3.org>
Message-Id: <44981AE1-5B65-4C5A-BD0C-53B922EA9311@evilfunhouse.com>
To: Andy Seaborne <andy.seaborne@talis.com>
On Jun 4, 2010, at 7:32 AM, Andy Seaborne wrote:

> Another possibility is all subjects + all objects as subjects and objects are the only things returnable by paths.
> 
> Gives a count of 2 for
> SELECT (COUNT(*) AS ?count) WHERE { ?start :p{0} ?end }

I considered that, but thought that we might want to be able to do this:

SELECT ?label WHERE {
	?p rdfs:subPropertyOf* rdfs:label .
	?s ?p ?label .
}

Would the * experience the same restriction on zero-length paths as the fixed-length {0}? If so, it seems that this query wouldn't work if there were no rdfs:label subproperties and no statements with rdfs:label as the subject/object.

.greg
Received on Friday, 4 June 2010 13:23:13 GMT

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