W3C home > Mailing lists > Public > public-rdf-wg@w3.org > March 2012

Re: New Proposal (6.1) for GRAPHS

From: Sandro Hawke <sandro@w3.org>
Date: Wed, 28 Mar 2012 10:25:26 -0400
To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
Cc: public-rdf-wg <public-rdf-wg@w3.org>
Message-ID: <1332944726.3423.113.camel@waldron>
On Wed, 2012-03-28 at 10:10 -0400, Peter F. Patel-Schneider wrote:
> Wow!
> 
> The graph semantics includes quite a bit of new stuff:

I am, of course, leaving defining the formal semantics to people who are
actually good at that stuff.   I'm just trying to convey they idea with
some formal-ish language and some test cases.

> owl:sameAs as equality

That's just used to express test cases.

> functional relationships
> partially reflexive relationships

Those exist....  Is it odd to define a relationship and say, in the
specification, that it is functional?    rdf/rdfs define lots of
relations; a few of them like rdf:first and rdf:rest perhaps should have
been defined as functional.  (Of course, that would have snuck equality
reasoning into RDF, which I guess is why it didn't happen.   Maybe
that's a problem with rdf:hasGraph?)

> The special status of the rdf:Graph class is rather unusual.
> 
> The proposal leaves open just what an RDF graph is in the semantics.  Is it 
> just a graph (so that its syntax matters), or is it a set of interpretations 
> (so that what matters is its RDF meaning)?

Your terms confuse me a little.  I mean rdf:Graph to be the class of RDF
Graphs, that is, every instance of rdf:Graph is a mathematical set of
(s,p,o) triples, where s is a node with an optional IRI label, etc.

   -- Sandro
> 
> peter
> 
> 
> On 03/27/2012 10:23 PM, Sandro Hawke wrote:
> > I've written up design 6 (originally suggested by Andy) in more
> > detail.  I've called in 6.1 since I've change/added a few details that
> > Andy might not agree with.  Eric has started writing up how the use
> > cases are addressed by this proposal.
> >
> > This proposal addresses all 15 of our old open issues concerning graphs.
> > (I'm sure it will have its own issues, though.)
> >
> > The basic idea is to use trig syntax, and to support the different
> > desired relationships between labels and their graphs via class
> > information on the labels.  In particular, according to this proposal,
> > in this trig document:
> >
> >     <u1>  {<a>  <b>  <c>  }
> >
> > ... we only know that<u1>  is some kind of label for the RDF Graph<a>
> > <b>  <c>, like today.  However, in his trig document:
> >
> >     {<u2>  a rdf:Graph }
> >     <u2>  {<a>  <b>  <c>  }
> >
> > we know that<u2>  is an rdf:Graph and, what's more, we know that<u2>
> > actually is the RDF Graph {<a>  <b>  <c>  }.  That is, in this case, we
> > know that URL "u2" is a name we can use in RDF to refer to that g-snap.
> >
> > Details are here: http://www.w3.org/2011/rdf-wg/wiki/Graphs_Design_6.1
> >
> > That page includes answers to all the current GRAPHS issues, including
> > ISSUE-5, ISSUE-14, etc.
> >
> > Eric has started going through Why Graphs and adding the examples as
> > addressed by Proposal 6.1:
> > http://www.w3.org/2011/rdf-wg/wiki/Why_Graphs_6.1
> >
> >       -- Sandro (with Eric nearby)
> >
> >
> 
Received on Wednesday, 28 March 2012 14:26:09 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:25:47 GMT