W3C home > Mailing lists > Public > public-linked-json@w3.org > February 2013

Re: Problem with auto-generated fragment IDs for graph names

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Mon, 18 Feb 2013 16:17:23 +0000
Message-ID: <51225413.6030407@epimorphics.com>
To: public-linked-json@w3.org, RDF-WG <public-rdf-wg@w3.org>


On 18/02/13 15:49, Markus Lanthaler wrote:
>> } } The system can also save this info in a format which other
>> systems can consume: { _:0x1234 a sioc:Post . _:0x1234 sioc:topic
>> "RDF is easy" . _:0x1234 sioc:reply _:0xabcd . _:0xabcd a
>> sioc:Post" . _:0xabcd sioc:topic "Named graphs are easy" . }
>> _:0x1234 { x:assertions x:expressedAs x:triples . }
>
> I was talking about the fact that bNodes MUST denote the graph to
> make this work.

The data says that

http://sioc-project.org/ontology#term_Post

_:0x1234 a sioc:Post

a sioc:Post is a document, which may be parsed to get a graph, or
several graphs, or none.  It may have other things in it as well.  It is
not a graph.

"""
Posts will have content and may also have attached files, which can be
edited or deleted by the Moderator of the Forum that contains the Post.
"""

_:0x1234 {
      x:assertions x:expressedAs x:triples .
    }

is a labelling of a graph (value).

So there is some relationship (not here defined) to the graph and that
is in the dataset structure.  In your previous message you talked about
"navigate" and "bnode identifiers".  I understood your description as
structural navigation of a datastructure from parsing.  Was that right?

You get would get from  _:0x1234 to the graph by looking in the dataset
structure (which is a map) if bnodes were allowed.  At this level, of
concrete graph structures, bnode label or a IRI string would serve the
same purpose using e.g. relative URIs (and a per-parse random base URI
making it only findable locally).  It's a local structural identifier.

> Could someone please give me a concrete example where it wouldn't
> make  sense that IRI labeling a named graph denotes it.

To reiterate a previous email:

The most common usage in real use that I have seen is using the URL of
the location where graph was read from.  For many applications the
g-box/g-snap distinction is simply not of interest.

	Andy
Received on Monday, 18 February 2013 16:17:56 GMT

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