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  • From: "Norman Gray" <norman@a...>
  • To: "Liam R. E. Quin" <liam@w...>
  • Date: Wed, 05 Oct 2016 18:17:26 +0100

Liam, hello.

On 5 Oct 2016, at 18:01, Liam R. E. Quin wrote:

It turns out even RDF has moved away from triples - an RDF "named
graph" associates (implicitly) additional information with each triple.

For example, consider needing to track the date on which each fact was
entered into a database. If you store that as a separate triple (on
such-and-such a date triple-id foo was added by bar (oops that's four))
you need to record when that information was added and by whom.
I think that might be an exaggeration. Some _implementations_ of triple stores might usefully store such extended provenance information, in the same way that some XML parsers or databases might document that they preserve attribute order. That doesn't meant that 'XML has moved away from unordered attributes'.

'Named graphs' are different. There, there's a mild extension (formally standardised, I _think_) of the RDF model, to include the name of the graph in which the statement 'Alice knows Bob' is asserted. Such graphs are supported in 'quad stores'. Such provenance turns out to be rather painful to express in bare RDF, to the extent that the extension is often useful.

All the best,

Norman


--
Norman Gray : https://nxg.me.uk
SUPA School of Physics and Astronomy, University of Glasgow, UK


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