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Re: Blank nodes as predicates Re: Blank Nodes Re: Toward easier RDF: a proposal

From: Nathan Rixham <nathan@webr3.org>
Date: Fri, 23 Nov 2018 00:31:13 +0000
Message-ID: <CANiy74x9KMAe42hTCyiJuT7U=NBZZzW3yjU=fH=g1ttP6q_cPw@mail.gmail.com>
To: David Booth <david@dbooth.org>
Cc: Tim Berners-Lee <timbl@w3.org>, W3C Semantic Web IG <semantic-web@w3.org>
blank node identifiers in a surface syntax are a pita, issue causing,
troublesome, discussion causing, skolemization causing

as for blank nodes themselves, I see no issue personally, or reason to
preclude them from any position in a triple - I'd rather have no IRI than a
useless one.

I can't remember ever seeing somebody say I want to have two json objects
in a document that are the same json object but encoded and presented as
two in that document, using some random identifier only valid to this
serialization of the data to allow me to see they should be considered the
same document, with x,y,z rules to combine them together and deserialize
then reserialize, perhaps with skolemization of ... please no.

Graph = Set of Triple
Triple = Node, Node, Node

Why complicate it further?



On Thu, Nov 22, 2018 at 11:52 PM David Booth <david@dbooth.org> wrote:

> On 11/22/18 9:14 AM, Tim Berners-Lee wrote:
> >> On 2018-11 -22, at 13:54, Martin G. Skjæveland <martige@ifi.uio.no>
> wrote:
> >> On 22/11/18 13:02, Tim Berners-Lee wrote:
> >>>> On 2018-11 -21, at 22:40, David Booth wrote:
> >>>> Blank nodes are special second-class citizens
> >>>> in RDF.  They cannot be used as predicates,
> >>> Agreed it messes up the symmetry.  Actually in most of my code you can
> use a blank node as a predicate.  That said, RDF is unusual in having as
> much symmetry.
> >>
> >> I like symmetry. Can we get a ✅ for blank nodes as predicates too?
> >
> > Yes, please!
>
> Not so fast please.  While I fully agree with the symmetry objective, I
> think adding *more* blank nodes would be going in exactly the *wrong*
> direction.   We *do* need the convenience that blank nodes currently
> provide, but we *don't* need blank nodes themselves, as Skolem IRIs have
> already demonstrated.
>
> IMO a much better route for *easier* RDF would be to *eliminate* blank
> nodes entirely -- or at least make them invisible to users -- while
> *still* retaining the convenience that they currently provide.  I think
> this is achievable, but it will require some creativity and careful
> engineering, to:
>
>   - Make IRIs *easy* to allocate; and
>
>   - Adopt higher-level RDF language constructs that eliminate or hide
> blank nodes.
>
> As you suggest in a separate message, I think the implicit blank node
> constructs of [] and () that N3 and Turtle provide are an excellent step
> toward meeting the second of these requirements.  But I don't think they
> are quite enough.
>
> David Booth
>
>
Received on Friday, 23 November 2018 00:31:47 UTC

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