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Re: Skolemization and RDF Semantics

From: Steve Harris <steve.harris@garlik.com>
Date: Tue, 19 Apr 2011 17:53:44 +0100
Cc: Pat Hayes <phayes@ihmc.us>, Ivan Herman <ivan@w3.org>, Dan Brickley <danbri@danbri.org>, David Wood <dpw@talis.com>, "public-rdf-wg@w3.org" <public-rdf-wg@w3.org>
Message-Id: <62A23DF0-EE7D-47AB-8FC3-0AF159DC5F7B@garlik.com>
To: Alex Hall <alexhall@revelytix.com>
On 2011-04-19, at 15:24, Alex Hall wrote:
> FWIW, some (many? most?) triple store implementations provide what might be called a weak form of skolemization at the API level, in that the bNode object ('object' in the programming language sense of the word) often encodes the internal identifier.  When the object is passed back to the store in a subsequent query or update, the store can recognize the object as a bNode that originated from a local graph and dereference the identifier to find the internal node.
> 
> Using bNode identifiers this way is probably an abuse of how they were originally intended, but it's also extremely useful for following your nose within the context of a single graph without having to formulate a monstrous SPARQL query to find the bNode you're looking for and pull in all of its properties in one fell swoop.  As a consumer of RDF data, if the same feature were exposed via SPARQL then I don't really care how it happens, I'll jump for joy.  As a WG member, I do recognize that it's our task to work out the "how it happens" part :-)

Exactly, that's how we got to the proposal, to try and codify current practice, and to make it legitimate / sanctioned / whatever.

- Steve

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Received on Tuesday, 19 April 2011 16:54:13 GMT

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