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Re: RDF* vs RDF vs named graphs

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Mon, 30 Nov 2020 12:56:10 +0100
To: Miel Vander Sande <miel.vandersande@meemoo.be>
Cc: "public-rdf-star@w3.org" <public-rdf-star@w3.org>
Message-ID: <6dc1aa74-9784-506c-c927-2505a8617013@emse.fr>
RDF reification has a standard formal semantics (a very weak one).
Named graphs don't, but there are formal semantics candidates for them.

What the discussion of RDF* semantics bring is the opportunity to define 
a stronger semantics for embedded triples than RDF reification.

Also, this opportunity may bring something new to the subject of the 
semantics of named graphs and RDF datasets.

However, the way the discussion is going seems to drive us towards a 
very weak semantics for embedded triples as well, thus perhaps, a missed 
opportunity.


--AZ


Le 30/11/2020 à 09:48, Miel Vander Sande a écrit :
> Just like RDF reification, named graphs have been around without formal 
> semantics. We have an attempt at the former with RDF*. Including the 
> latter is a question of scoping and there is nothing that prevents 
> anyone to take a crack at the latter. TBH, I think this fits in the 
> scope of what the N3 group is doing and they are making efforts to 
> harmonize with RDF*. In the meantime, you can still use the current 
> Named Graphs as you see fit (see also Olaf's answer to Martynas). For 
> me, describing a statement directly (RDF*) is significantly different 
> from describing an identifier which is "somehow" related to a set of 
> statements (Named Graph). I would like to know what this "somehow" 
> relation means if I'm migrating a dataset full of NG's to another system.
> 
> I appreciate the work this group is doing in terms of making the 
> interpretation of reification clear and usable. Its main goal is still 
> to provide compatibility with the PG world, where properties over a 
> group of edges simply doesn't exist. I think this limited scope actually 
> helps getting somewhere within reasonable time.
> 
> Best,
> 
> Miel
> 
> Op ma 30 nov. 2020 om 01:43 schreef Patrick J Hayes <phayes@ihmc.us 
> <mailto:phayes@ihmc.us>>:
> 
>     I agree. When I first met the idea of RDF* I made this same point to
>     Thomas, and we had some correspondence on the topic. I came to the
>     conclusion that my expending effort towards the development of RDF*
>     would be a waste of time.
> 
>     Pat
> 
>      > On Nov 29, 2020, at 4:43 PM, Peter F. Patel-Schneider
>     <pfpschneider@gmail.com <mailto:pfpschneider@gmail.com>> wrote:
>      >
>      > I've been thinking about the expressive power of RDF* related to the
>      > expressive power of RDF, at least the versions of RDF* that have
>     been proposed
>      > so far.
>      >
>      > As far as I can tell anything that can be done in RDF* can be
>     easily done in
>      > RDF by using standard
>      > RDF reification techniques, perhaps slightly modified (e.g., to
>     account for
>      > malformed literals), with extra properties linking to syntactic
>     encodings to
>      > achieve referential opacity.
>      >
>      > But named graphs are more expressive than RDF* in a certain
>     sense, as named
>      > graphs allow multiple "embedded" triples to be collected together.
>      >
>      >
>      >
>      > peter
>      >
>      >
>      >
> 
> 

-- 
Antoine Zimmermann
Institut Henri Fayol
École des Mines de Saint-Étienne
158 cours Fauriel
CS 62362
42023 Saint-Étienne Cedex 2
France
Tél:+33(0)4 77 42 66 03
Fax:+33(0)4 77 42 66 66
http://www.emse.fr/~zimmermann/
Member of team Connected Intelligence, Laboratoire Hubert Curien
Received on Monday, 30 November 2020 11:56:24 UTC

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