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RE: RDF Terminologicus

From: McBride, Brian <bwm@hplb.hpl.hp.com>
Date: Fri, 5 Jan 2001 12:28:57 -0000
Message-ID: <5E13A1874524D411A876006008CD059F2395CB@0-mail-1.hpl.hp.com>
To: "RDF Interest (E-mail)" <www-rdf-interest@w3.org>
Cc: "'Graham Klyne'" <GK@Dial.pipex.com>
Hi Graham,

> I've started an HTML document with these in.  In reification 
> of a graph, 
> would you allow "collection" rather than "bag", to allow some 
> wiggle room 
> in the exact representation?

Right now, I'd probably say it should be a bag, but thats not as
negative as it sounds.  I think its important to position this
concept relative to the context concept you have been championing.

I divide these discussions into two tracks:

  o clarifying the current specs
  o future developments

The reification of a graph concept to me is in the clarifying the
current specs track.  To me, contexts are an important new 
development.

I believe that contexts have extra semantics
over just being a collection of statements, that they need the
machinery of the logic layer - interpretations and that sort of
thing to do them properly.  The RDF layer alone does not have the
machinery  - all it can do are collections of statements.

So in terms of the RDF layer, a graph is an unordered collection
of statements.  BAG is the right construct for representing that.
SEQ and ALT just don't make sense.  Further, m&s talks about 
description elements representing bags of reified statements which
maps nicely onto the language that those bags and their contents
are the reifications of the subgraphs defined by a description
element.

I share your concerns about the current definitions of bags - have
ordered properties for the members of an unordered collection just
seems bizare to me.  So I'd be sympathetic to a future spec defining
improved collections.  But right now BAG is what we have, so in terms
of working with the current spec, I think BAG is right.

Contexts will bring a much richer and powerful semantics.

Brian


> 
> #g
> --
> 
> 
> >How about:
> >
> >RDF Graph:
> >
> >   a set of RDF statements.
> >
> >Reification of an RDF Graph
> >
> >   A bag containing the reifications of the statements in 
> the RDF graph
> >
> >Reified Graph
> >
> >   The bag in the reification of an RDF graph.
> >
> >Brian
> >
> > > -----Original Message-----
> > > From: Graham Klyne [mailto:GK@Dial.pipex.com]
> > > Sent: 01 January 2001 17:32
> > > To: Bill de hÓra
> > > Cc: RDF-IG
> > > Subject: Re: RDF Terminologicus
> > >
> > >
> > > OK, here's my shot:
> > >
> > >
> > > Web Resource:
> > >    Anything that is identified by a URI [RRC2396].
> > >
> > > RDF Resource:
> > >    [See RDF M&S section 5]  Note that an RDF resource is not
> > > necessarily a
> > > web resource,
> > >    though any web resource can be an RDF
> > > resource.  Consider:  http://foo.com/#a and
> > >    http://foo.com/#b name distinct RDF resources, but not
> > > distinct web
> > > resources.
> > >
> > > RDF Statement, Statement:
> > >    [See RDFM&S section 5]
> > >
> > > RDF Description:
> > >    [See RDFM&S]
> > >    Construct containing representations of a number of 
> RDF statements
> > >    about a specific RDF resource, and possibly some
> > > additional statements.
> > >
> > > Description [of]:
> > >    (As opposed to RDF Description)
> > >    Language or data structure providing information about
> > > some entity or
> > >    concept.
> > >
> > > Stand for:
> > >    A labelled entity that is used in descriptions indicate
> > > some entity or
> > >    concept.
> > >
> > > Reification (of a statement):
> > >    [See RDFM&S section 5]  A resource that stands for the 
> statement
> > > together with
> > >    the four statements that describe the statement.   In my
> > > opinion, a
> > > reification of
> > >    a statement is not unique:  there may be more than one
> > > reification of
> > > any given
> > >    statement.
> > >
> > > Representation:
> > >    A data structure (abstract or concrete) that captures some
> > > essential
> > >    properties of some entity or concept.
> > >
> > > Representing [x]:
> > >    Being a representation of [x] (see above)
> > >
> > > Context:
> > >    An environment within which some statements are taken 
> to be true.
> > >
> > > Quoting:
> > >    A reference to a statement without necessarily making any
> > > assertion about
> > >    its truth or falsity.
> > >
> > > Stating:
> > >    An assertion that some statement is true in some context.
> > > (or should that be:
> > >    An assertion in some context that some statement is true.
> > > ?)
> > >    NOTE:  this assertion is a statement separate from the
> > >    statement asserted to be true.
> > >
> > > Model:
> > >    (I've tried to stop using this term, since it has a 
> quite specific
> > >    meaning to logicians, that is not the same as what I would
> > > regard as
> > >    its "natural" meaning.)
> > >
> > >
> > > #g
> > > ------------
> > > Graham Klyne
> > > (GK@ACM.ORG)
> > >
> 
> ------------
> Graham Klyne
> (GK@ACM.ORG)
> 
Received on Friday, 5 January 2001 07:29:06 GMT

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