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Re: Slides for Berlin Data Workshop

From: Sandro Hawke <sandro@hawke.org>
Date: Tue, 26 Feb 2019 08:39:56 -0500
To: public-linked-json@w3.org
Message-ID: <eba1308a-dbdf-9655-2b75-cc1d51661791@hawke.org>
On 2/26/19 4:49 AM, Antoine Zimmermann wrote:
> Hello,
>
>
> 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.
>

This is a potentially large topic.  Perhaps we can take it to github?  I 
wrote up this exact issue (in the context of the N3 CG), at 
https://github.com/w3c/N3/issues/1, so that's probably a good place to 
do it.

Gregg is advocating for Option 2, which I think has a lot of merit, 
although I agree it's not "the only reasonable interpretation".  I'd 
love to hear how you propose to, for example, publish graph metadata, 
Antoine.

I separated the logic question out to 
https://github.com/w3c/N3/issues/2, since I think it's distinguishable.  
My current applications (credibility/disinformation) are about 
provenance not about representing rules, so issue 1 is much more 
important to me right now.

   -- Sandro


> 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 N3logic.
>
> 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.
>
>
> Best,
> --AZ
>
> 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
>>
>>
>
Received on Tuesday, 26 February 2019 13:40:21 UTC

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