W3C home > Mailing lists > Public > public-rdf-wg@w3.org > December 2011

Re: dataset semantics

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Sat, 17 Dec 2011 13:16:43 -0500
Message-ID: <4EECDC8B.3050207@thefigtrees.net>
To: Pat Hayes <phayes@ihmc.us>
CC: Sandro Hawke <sandro@w3.org>, David Wood <david@3roundstones.com>, RDF WG <public-rdf-wg@w3.org>
On 12/17/2011 10:58 AM, Pat Hayes wrote:
> On Dec 16, 2011, at 11:43 PM, Sandro Hawke wrote:
>> Another example of the relationship is something I gather
>> Cambridge Semantics uses, which I'll call subjectOf.   (In one of
>> their deployment modes, triples are divided into two type, which
>> I'll call A and B, based on which predicate they use.  The dataset
>> is constructed such that for each<U, G>  in the dataset, every
>> type-A triple in G is of the form {<U>  ?P ?O }.  The type-B
>> triples are a little more complicated.)  In this case, the dataset
>> being true would imply the dataset being segmented in this
>> complicated but useful way.
> With all respect to Cambridge Semantics, if they are the only user of
> this odd convention, then I really dont think we as a WG should even
> be considering standardizing it. Unless someone can make a case for
> why it is going to be generally useful.

For the record, we're not asking that any of this should be 
standardized. In fact, we'd probably object to that :-)

> And in any case, this sounds like a syntactic restriction rather than
> a semantic condition. Having the dataset be segmented is not going to
> alter the interpretations of any of the triples (is it?). So the
> semantics (and hence the entailments) can ignore this.

Right, that's exactly how we feel about it.


>> It's *rather* tempting to just use triples for this, making
>> graphState, graphStateWas, subjectOf, etc, be predicates.   That
>> way the semantics of datasets would be much simpler, with the
>> complications bundled into the semantics of those particular
>> predicates.
>> I'm guess I'm suggesting extending the definition of dataset to be
>> a default graph and rather than a set of pairs<U,G>, be a set of
>> triples <U, R, G>, where R is optional.  If R is omitted, you have
>> the kind of dataset we're used to now, where we have no idea what
>> that relation is supposed to be (unless the author tells us
>> humans).
> So I should interpret<U, R, G>  to mean that the relation R holds
> between the resource U and the graph G, and U is *never* simply a
> name of the graph, is that right? That is we never have the graph
> simply being the resource identified by the IRI ?
>>> Can one assert a dataset (ie claim it to be true)?
>> Yes.
>>> How does one do that?
>> The same way you do with RDF.  It kind of depends on your
>> application. Maybe you publish it on the web; maybe you send it to
>> some agent; maybe you publish it and send the URL somewhere, etc.
> And is this in fact done? Do people transmit SPARQL datasets around
> the Web? What would be a typical transaction involving a dataset?
> When it is done, what typically happens to the RDF triples in the
> graphs in the dataset? Do other applications extract them and mash
> them up with other RDF? Or are they always kept in their dataset
> 'context'?
> Pat
>> -- Sandro
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Received on Saturday, 17 December 2011 18:17:10 UTC

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