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RE: dataset semantics -- was Re: ACTION-278: grammar for TriG

From: Markus Lanthaler <markus.lanthaler@gmx.net>
Date: Sun, 7 Jul 2013 14:48:38 +0200
To: <public-rdf-wg@w3.org>
Message-ID: <00ab01ce7b10$4eb570d0$ec205270$@lanthaler@gmx.net>
On Sunday, July 07, 2013 1:35 PM, Sandro Hawke wrote:
> It's not that the name doesn't denote the graph, it's that it doesn't
> *necessarily* denote the graph.  Eric's example will work fine in a
> context where suitable dataset semantics are in use.

Right. It is exactly that ambiguity that worries me.

> Earlier, I gave the
> example that this could be flagged by having the triple { <> a
> rdf:BoundDataset } in the default graph. Another name for that might be
> "Direct".

A more granular alternative would be to define rdf:Graph which could be used
to type things as "denoting graph name".

> In contrast, we might also have a WebCacheDataset, or WebViewDataset, or
> GraphStoreSnapshot, in which the graph names denote g-boxes whose
> contents are the associated graphs. (Change-over-time here is a problem,
> but it's the same problem we have throughout the RDF world.)
> Now that we have blank node graph names available, I'm thinking the most
> popular dataset semantics will be a combination: for URLs, the
> graph-name denotes the g-box; for blank nodes, the graph-name denotes
> the graph.

+1, yet we make it more complicated than necessary to express those
semantics IMO

> I'm not sure which way to treat genids - it depends if we
> want the genid-creator to be obligated/encouraged to publish the graph
> at the genid URL.
> But this is too speculative to put into a document that's slated to
> become a REC by the end of the year.  So instead, dataset semantics are
> an extensibility point, and we can experiment for a while.

... probably leading to interoperability problems till we feel ready to make
a decision at which point it probably is too late as we can't modify the
semantics of existing data anymore.

Sorry for being so negative but I think we are making a huge mistake here.

Markus Lanthaler
Received on Sunday, 7 July 2013 12:49:09 UTC

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