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Re: Slides for Berlin Data Workshop

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Tue, 26 Feb 2019 10:49:21 +0100
To: public-linked-json@w3.org
Message-ID: <372f07f1-a3dc-77d9-5295-b268c680504f@emse.fr>

This is my first email to the JSON-LD CG mailing list, so let me 
introduce myself: I am Antoine, working on semantic web technologies 
since 2004 as a researcher. I participated in the RDF 1.1 working group, 
quite actively, where my primary interest was RDF semantics.

Concerning your slides, Gregg, on slide 2, you say "The only reasonable 
interpretation of graphs named via blank node (...) is that the blank 
node denotes the graph it names".

Graph names can be interpreted in many ways, lots of which are 
considered reasonable by those who advocate them.

In fact, the very people who introduced the concept of named graphs 
(Carroll et al. in 2004) defined a formal semantics according to which 
an RDF interpretation I satisfies ("conforms to", in their words) a 
named graph (n,g) iff I(n) = (n,g), that is, the name is interpreted as 
the named graph *pair*, not the graph.

Many people have used the idea of quads (that can be seen as a syntactic 
variation of the concept of named graphs) in very different ways, some 
of which are implemented in triple stores (e.g., spatio-temporal triple 
store Strabon).

In any case, defining the meaning of a JSON-LD document is not part of 
the JSON-LD group's mission. JSON-LD defines how to map a JSON-based 
format to the abstract RDF structures, then people interpret it as they 
want, possibly following other specs like RDF Semantics, OWL, SWRL, or 

Similarly, slide 5 is not about "Reasoning in JSON-LD": it is explaining 
how to map N3 formulas to JSON-LD. Then people can decide to interpret 
JSON-LD documents as N3, following slide 5 representation, and do *N3 
reasoning*, not "JSON-LD reasoning". They could also just map this 
representation to a normal RDF dataset and apply other kinds of reasoning.


Le 23/02/2019 à 23:50, Gregg Kellogg a écrit :
> The format for the Berlin Data Workshop [1] remains unclear, but I’ve prepared just a couple of slides to describe one way in which Anonymous Named Graphs in JSON-LD could support the property graph use case.
>> https://json-ld.org/presentations/JSON-LD-Support-for-Property-Graphs/ <https://json-ld.org/presentations/JSON-LD-Support-for-Property-Graphs/>
> There’s a short overview of new things in JSON-LD 1.1, and as a bonus, a sketch of how Notation3 reasoning might look in JSON-LD. (Hint, we really only need to invent a way to describe universal variables at the syntax level; reasoning should be universal based on obvious projections from Notation 3. The required extensions to RDF Datasets and better description of reasoning semantics are work to be done elsewhere).
> Gregg Kellogg
> gregg@greggkellogg.net
> [1] https://www.w3.org/Data/events/data-ws-2019/schedule.html

Antoine Zimmermann
Institut Henri Fayol
École des Mines de Saint-Étienne
158 cours Fauriel
CS 62362
42023 Saint-Étienne Cedex 2
Tél:+33(0)4 77 42 66 03
Fax:+33(0)4 77 42 66 66
Member of team Connected Intelligence, Laboratoire Hubert Curien
Received on Tuesday, 26 February 2019 09:49:50 UTC

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