W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > November 2002

defn of blank nodes and triples RE: Review of 21-Nov concepts draft, part 3, sect 3-end

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Fri, 29 Nov 2002 09:59:28 +0100
To: "Graham Klyne" <GK@NineByNine.org>, "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Cc: <w3c-rdfcore-wg@w3.org>
Message-ID: <BHEGLCKMOHGLGNOKPGHDEENFCAAA.jjc@hpl.hp.com>

[[This is an offlist thread I am moving on-list because I think this is of
wider interest]]

Graham and I are discussing the definition of a triple.

In the text of the current published draft:

http://www.w3.org/TR/2002/WD-rdf-concepts-20021108/#xtocid103646

which I essentially want to leave unchanged, the term blank node is not part
of the defintion of a triple, instead blank node is defined later, depending
on this definition of triple.

It is, however, confusing to suppress the key concept of blank node to the
extent that the current published draft does.

There is something quite elegant about the current negative definition of a
blank node - what is a blank node? we don't tell you, we only tell you what
it isn't. This elegance does capture something of the elusiveness of blank
nodes.

Graham prefers text like:

Graham:
> > An RDF triple contains three components:
> >
> > the subject, which is an RDF URI reference or a blank node
> > the predicate, which is an RDF URI reference
> > the object, which is an RDF URI reference, a literal or a blank node
> >

This is reminiscient of Pat's  earlier texts. Pat made these work by having
an explicit ready supply of blank nodes.
My text has an implicit ready supply of nodes.

Graham:
> Well, IIRC, you say later that a blank noide is one that isn't a URI or a
> literal.  I considered that the term blank node here would just be a
> forward reference to that description, as are URI reference and literal.
>
> I don't think this is critical.

My worry is that we then get to a circular defn:

Currently:

blank node depends on graph depends on triple depends on (uriref and
literal).

If blank node is added to the defn of triple we get:

blank node depends on graph depends on triple depends on (uriref and literal
and blank node).


Any thoughts?

Jeremy
Received on Friday, 29 November 2002 03:59:38 EST

This archive was generated by hypermail pre-2.1.9 : Wednesday, 3 September 2003 09:54:11 EDT