W3C home > Mailing lists > Public > public-rdf-wg@w3.org > August 2012

Re: Minimal dataset semantics

From: Richard Cyganiak <richard@cyganiak.de>
Date: Thu, 23 Aug 2012 21:05:31 +0100
Cc: Pat Hayes <phayes@ihmc.us>, RDF Working Group WG <public-rdf-wg@w3.org>
Message-Id: <61C89D0B-C266-4ECD-9167-B6B5086343E5@cyganiak.de>
To: Sandro Hawke <sandro@w3.org>
On 23 Aug 2012, at 20:09, Sandro Hawke wrote:
> This was a surprise to me, too, but Lee reported that they often wrote TriG like this:
> 
> === file 1
> ... stuff
> 
> <g1> { ... some triples that go in g1 ... }
> 
> ... more stuff
> 
> <g1> { ... more triples that go in g1 ... }
> 
> === file 2
> 
> <g1> { ... even more triples that go in g1 ...}
> 
> ============
> 
> When I suggested that file1 and file2 contradicted each other, I recall several people agreeing with Lee.  They want to be able to have the triples in g1 spread out throughout multiple locations in multiple files.
> 
> When we talked about this, it seemed to many people to be perfectly natural, to be "Open World."   Saying that some triples are in some named graphs isn't as useful as enumerating all the triples in that named graph (and declaring you are doing so), but it's not useless.

FWIW, this use case works well with truth-based semantics. Essentially, loading both TriG files amounts to asserting that the triples from both graphs are true in context <g1>. (Apologies for using the word "context".)

> I agree the machinery of partial-graph quoting semantics is the same as that of a very limited truth semantics, as you describe it.    I think the intuitions and motivations are quite different, however.

Why?

> Also, to be clear, I'm not trying to advocate for any particular semantics -- I just would like something that gets folks closer to being able to address the use cases.   I think complete-graph quoting semantics is probably that

I don't think so. Complete-graph quoting semantics does a bad job at explaining SPARQL Entailment Regimes, can't be extended, and doesn't address the Sindice use case of parsing microformats (that is, structured but non-RDF data) from the web. But anyways, it looks like no one is really advocating complete-graph quoting any more.

Best,
Richard



> but I took guidance from that 25 April meeting that partial-graph quoting semantics was a more promising route.  
> In my implementation, as I recall, partial worked fine, with the usual RDF best-practice that systems semantically *can* drop triples but in general they do/should not.
Received on Thursday, 23 August 2012 20:06:11 UTC

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