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Re: Using named graphs to model PROV's Accounts

From: Sandro Hawke <sandro@w3.org>
Date: Tue, 11 Oct 2011 19:04:40 -0400
To: Andy Seaborne <andy.seaborne@epimorphics.com>
Cc: public-rdf-prov@w3.org
Message-ID: <1318374280.25065.53.camel@waldron>
On Tue, 2011-10-11 at 23:24 +0100, Andy Seaborne wrote:
> 
> On 11/10/11 21:43, Sandro Hawke wrote:
> > On Tue, 2011-10-11 at 20:32 +0100, Andy Seaborne wrote:
> >>
> >> On 11/10/11 19:11, Timothy Lebo wrote:
> >>> rdf-prov,
> >>>
> >>> In preparation for the RDF WG F2F this week, I wanted to provide some discussion on using named graphs to address some provenance modeling.
> >>>
> >>> I have updated http://www.w3.org/2011/prov/wiki/Using_named_graphs_to_model_Accounts to reflect some feedback and extend the discussion on named graphs.
> >>>
> >>> In particular, I discuss:
> >>>
> >>> * reuse of the SPARQL Service Description vocabulary to describe named graphs.
> >>> * Meta Named Graph pairs,
> >>> * a simple application of these to create Cache Graphs
> >>> * the importance of modeling the "location" of a graph to disambiguate many graphs with the same name.
> >>>
> >>> These components are needed to model PROV's notion of Accounts, which permit different agents to assert different views of the same "event" (i.e., ProcessExecution). I hope to wrap up all of this into a final proposal by the end of the week.
> >>>
> >>> Any suggestions or comments appreciated.
> >>
> >>
> >> As a principle (of AWWW), one name can only refer to one thing.
> >>
> >> "graph" here seems to refer to graph-a-location but also "graph the
> >> contents of the location".  But those are different things.
> >
> >
> > I might be confused, but it looks to me like Tim is making the best of a
> > bad situation: he's trying to use the "name" in a name-graph pair to
> > identify a graph/gbox, but he's recognizing that [ because we haven't
> > adopted my Web Semantics for Datasets proposal :-) ] the scope of that
> > binding is only a single dataset.  He's calling the dataset identifier
> > the "location".     At least that's how I'm reading it.
> 
> Sandro - I'm surprised you use a phrase like "bad situation".  It's hard 
> to see how this can progress if you are starting from that position.

Sorry -- I try to use the clearest language I can, sometimes at the risk
of being impolitic.   I certainly don't mean to be insulting or to put
anyone down.  There's not a person I've spent time with in a W3C Working
Group who I don't admire.

General comment on such things: I think there are several bad aspects to
the designs in W3C specs, and I try not to mince words in saying so, but
I can't think of one I blame on a person or even which has caused me to
have less respect for a person.  In every case that I know if, it's a
case of reasonable engineering tradeoffs in the face of multiple
unknowns and time pressure.   In retrospect, it sometimes becomes clear
a different choice would have been better, but if it was a reasonable
choice given the information at hand (and in my experience at W3C it
always has been), that regret doesn't reflect badly on the person or
people who made that choice. 

> Do you agree that for AWWW and for RDF, one URI denotes one thing?

Absolutely, yes.

Perhaps I'm not communicating my point well.

The "bad situation" is that the "names" in RDF datasets, even though
they are syntactically IRIs, do not in the current specs or in current
practice denote the associated g-box (or g-snap, or anything like that).
I understand why the SPARQL spec is like that, and I don't blame anyone,
but I think it's a kind of unfortunate situation.   I think the Semantic
Web would work better if the name part of an RDF dataset were understood
to denote the g-box (or maybe g-snap, or something similar).  That's
what I'm trying to move us toward with the "Web Semantics for Datasets"
proposal.

> (this of course does not stop inappropriate modelling and use but we 
> can't stop that by architecture anyway).

No, that's what legislation is for.    [ just kidding! ]


    -- Sandro   :-)

> 	Andy
> 
> >
> >       -- Sandro
> >
> >
> >
> 
Received on Tuesday, 11 October 2011 23:04:48 GMT

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