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

Re: suggested wording for removing weasels from MT

From: Dan Connolly <connolly@w3.org>
Date: 23 Apr 2002 15:19:23 -0500
To: Pat Hayes <phayes@ai.uwf.edu>
Cc: w3c-rdfcore-wg@w3.org
Message-Id: <1019593164.5164.2759.camel@dirk>
On Tue, 2002-04-23 at 14:52, Pat Hayes wrote:
> >On Mon, 2002-04-22 at 16:58, Pat Hayes wrote:
> >I'd really rather just take it out until we're more
> >clear about how to use the hook.
> Well, I have to say something about what it means to 'assert' an RDF 
> graph. The document already makes some vague noises about one graph 
> being taken to include a merge of any other graphs that are thought 
> to define its vocabulary,

It does? Where did that come from?

The nice thing about a model theory is that it *eliminates*
things like vague noises. I hope we have no vague noises
anywhere in the model theory spec.

> so it seemed harmless to add that some 
> users might want a graph to assert *less* than is actually in it. I 
> don't see this as a "hook", since it doesn't even hint at any way to 
> implement or use this,

No? I read it (and I think lots of other people would read it)
as saying "well, you know those entialment tests? sometimes
they work, but not always. It depends, really, on
fuzzy stuff that we're waving our hands around but not
actually specifying."

> just an acknowledgement that people do 
> sometimes do things like this (some of them people on the WG itself, 
> in fact)

For example?

> and a warning that the scope of the MT should be adjusted 
> accordingly whenever it is clear that this is being done.

>  The only 
> normative aspect of this is that the MT (now with no clauses in it 
> about unasserted triples) defines the content of whatever is 
> asserted; that is unambiguous and unqualified.

Yes, and the syntax spec tells us the connection between
a hunk of XML and what's asserted (i.e. a graph of asserted
triples). I want to make sure that the connection between
RDF/XML and the various entailments is rock solid, with no
weasel words in between.

> It relegates the whole 
> 'dark triples' issue to an area where the RDF spec is already vague 
> in any case (what counts as an 'assertion' of RDF content, in 
> general?)

That's not vague at all, to me. If you think it's vague
in some way, please give me an example so that we can
put it in the test suite to make it crystal clear.

> thus rendering it relatively harmless; but in any case, 
> that is where it belongs, rather than in the MT.
> Pat
> PS. I wonder why you are being so stern about this issue, Dan, since 
> being utterly rigid about RDF meaning being *exactly* fitted to RDF 
> graphs is about the only position that will guarantee that RDF will 
> be unusable as a foundation for the SW.

I accept that as your opinion. I disagree.

On the contrary: without a solid mathematical basis for RDF,
it has no role to play in building the Semantic Web.

I could be wrong. If so, I'd like to find out sooner rather
than later.

If being clear about what RDF is makes it clear that it's useless,
I'd prefer that to weasel words that allow everybody to be
happy when nobody actually agrees as to what's going on.

> I'm trying hard here to find 
> a way to make Tim's layer-cake diagram work, and you seem determined 
> to sabotage it.

I prefer to resolve conflicts at the earliest possible opportunity.
If the layer cake goes up in smoke as a result of being clear
what a hunk of RDF/XML means, then so be it. Let's do that
quickly so we can get on with something else.

Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Tuesday, 23 April 2002 16:19:16 UTC

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