Re: First meeting of our group

Having a hard time finding other references, but around the time the RDF 1.1 WG was completing TriG, there was a thought to do a follow-on which would be a super-set of TriG (TrigN3?) allowing more N3-like syntax. I have a branch in my implementation [1] which had a sample grammar [2] that would allow graphs to appear as the subject or object of a statement. I recall Sandro, Andy S., Eric P. and Gavin C. were involved in discussing this as well. This would have allowed something like the following (from Notation 3 Logic [3]):

{
  _:x :wrote _:y.
   _:y log:includes {_:z :weather _:w}.
  _:x :livesIn _:z
} log:implies {
  <Boston> :weather _:y
}.

to be syntactically valid (without describing what it means). My interpretation is that graphs can have blank-node names, so that dataset might be equivalent to the following:

_:g1 { _:x :wrote _:y.  _:y log:includes _:g2 . _:x :livesIn _:z}
_:g2 {_:z :weather _:w}
_:g3 {<Boston> :weather _:y}
_:g1 log:implies _:g3 .

There’s a separate conversation to be had about graphs being first-order resources (along with RDF* statements).

There was also some discussion in 2015 [4] on subject-lists:

:Alice, :Bob, :Charlie :hasFriend :Doug.

and for predicates:

:sandro foaf:firstName,vcard:firstName "Sandro"

and for graphs:

GRAPH :g1, :g2, :g3 { ... some triples }

Gregg Kellogg
gregg@greggkellogg.net

[1] https://github.com/ruby-rdf/rdf-trig/tree/feature/TrigN3
[2] https://github.com/ruby-rdf/rdf-trig/blob/feature/TrigN3/etc/trig.bnf <https://github.com/ruby-rdf/rdf-trig/blob/feature/TrigN3/etc/trig.bnf>
[3] https://www.w3.org/DesignIssues/Notation3.html
[4] https://lists.w3.org/Archives/Public/public-sparql-dev/2015JanMar/0030.html

> On Dec 11, 2018, at 9:03 AM, Doerthe Arndt <doerthe.arndt@ugent.be> wrote:
> 
> Dear all,
> 
> Now that Dave offered to provide us a W3C git (thank you once again!), we should move on to the next point and identify the topics we want to work on. I set up a doodle to find the right time for a  first meeting. Based on your answers so far, I thought that 16:00 UCT was the best time for such a meeting but if you think differently just let me know and I will adapt the doodle:
> 
> https://doodle.com/poll/h7xrxhuwfvy8aqmu <https://doodle.com/poll/h7xrxhuwfvy8aqmu>
> The list of open topics we discovered so far was (note that is an open list, I just summarize here what I remember):
> 
> Provide a formal semantics for N3, open issues there:
> Implicit quantification: scoping of universal variables and existential variables (blank nodes)
> Explicit quantification: what is the scope of @forSome and @forAll? Do we want to allow any URI as variable?
> Meaning of built-in functions: we need to agree on built-ins we want to see as part of N3 logic and formalise them. 
> Meaning of cited formulas: we need to agree on one formalisation for the meaning of cited formulas.
> Formalisation of a proof calculus (but this can only be done after fixing the meaning of formulas).
> Lists: lists are treated differently in RDF and N3 do we want to keep that? than we should clarify the relations of the standards.
> 
> 
> To agree on formal semantics we really should focus on the expected use cases and here I would like to get some insights. We especially need to know:
> Which built-ins do we need? Candidates are the ones which are already implemented for Cwm (https://www.w3.org/2000/10/swap/doc/CwmBuiltins <https://www.w3.org/2000/10/swap/doc/CwmBuiltins>), or the one identified by the RIF working group (https://www.w3.org/TR/rif-dtb/ <https://www.w3.org/TR/rif-dtb/>) or we could also look into the different functions which are available in SPARQL filters.
> How do want to use cited graphs: There is a whole list how the related concept TriG could be understood (https://www.w3.org/TR/rdf11-datasets/ <https://www.w3.org/TR/rdf11-datasets/>). Behind these there are for sure applications which drove the definitions and I think it could help to understand what these were. But I also think that all of you have ideas how to use the concepts, so maybe we could create examples?
> How expressive does the rule reasoning need to be? This will influence how we formalise the quantification, so I would like to know where you want to use N3 reasoning for.
> 
> 
> We should also keep the relation to other standards close:
> we should try to align with RDF where possible
> do we need a JSON-LD specification?
> what is the position towards TriG? Reification? RIF?
> 
> 
> Together with the formalisation we should also discuss whether we provide a reference implementation together
> I would like to add these topics to the git as soon as we have it, we can also all propose new issues, discuss them there and prioritize. I hope that we end up with a short list of things we all tackle together.
> 
> So, for a first step, please fill in the doodle till the end of the week.
> 
> Kind regards,
> Doerthe
> 
> 
> 
> -- 
> Dörthe Arndt
> Researcher Semantic Web
> imec - Ghent University - IDLab | Faculty of Engineering and Architecture | Department of Electronics and Information Systems
> Technologiepark-Zwijnaarde 19, 9052 Ghent, Belgium
> t: +32 9 331 49 59 | e: doerthe.arndt@ugent.be <mailto:doerthe.arndt@ugent.be>