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Re: N3 and N-Triples (was: RDF in HTML: Approaches)

From: Alberto Reggiori <areggiori@webweaving.org>
Date: Thu, 06 Jun 2002 16:17:48 +0200
Message-ID: <3CFF6F0C.80F61BE1@webweaving.org>
To: Graham Klyne <GK@ninebynine.org>
CC: "'RDF Interest'" <www-rdf-interest@w3.org>

Graham Klyne wrote:

> At 10:51 AM 6/6/02 +0100, Seaborne, Andy wrote:
> >If an RDF processor reads in the same file twice, are the bNodes the same or
> >different?
>
> I'd say "different".

I would say syntactically  "different" but semantically the "same".

> That sounds rather dodgy to me -- the model theory is quite clear that
> bnodes are not identified with anything outside the graph in which they
> appear -- if you start introducing identifiers that describe bNodes from
> "outside", you (a) need to have a way of scoping them to a particular graph
> instance, or (b) be very sure that they are unique.

yes bNodes are "anonymous" and they must not have a URI, but in a way or the
other they must have a kind of
LRI (Local Resource Identifier) for the savvy of software processors to refer
and talk about them :-)

How can we generate sensible and semanticful LRI then?

> Because of the way that bNode semantics are defined (essentially, as
> existential variables), I don't think it really matters if you have
> different bnodes in different places as long as the associated statements
> about them are "isomorphic" -- there's some recent discussion in the DAML
> list about "minimal identifying description" (MID) between Richard Fikes
> and Peter Patel-Schneider that might have some bearing.   I don't know
> where the web archive is, but look for messages starting about:

MID sounds interesting and I will have a look into it; while reading your
comment it beared in my mind DanB  "aggregation strategies" text [1].
Would MID help to smush triples then ?
How would we generate "primary keys" to join "tables" here? Has
daml:UnambiguousProperty been designed for that?

Another perhaps interesting methapor is about compilers and the generation of
position independent and relocatable code i.e. -fpic.
In fact, from this perspective I could look at bNodes like programming variables
and how they are used in the code e.g. perl hash or array references or C
pointers; when you code you never think how the actual source code will be
compiled and where in memory or disk the specific variable will be allocated
i.e. you do not think about syntax. The compiler instead will take care of that
for you and will generate offsets and displacements to properly run programs on
different memory areas, different media or on different machines. The point here
is the following:
Can't we use PIC like and other similar techniques to somehow sort out the
technical implementation of bNodes? :-)
Has object serialisation, RMI, RPC solved this problem already in the past?
Can't we invent some kind of "offsets" for bNodes?

my .002 euros

Alberto

[1] http://rdfweb.org/2001/01/design/smush.html
Received on Thursday, 6 June 2002 10:15:08 GMT

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