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Re: Final version of semantics

From: Dan Connolly <connolly@w3.org>
Date: Wed, 12 Nov 2003 17:47:39 -0600
To: pat hayes <phayes@ihmc.us>
Cc: w3c-rdfcore-wg@w3.org, Graham Klyne <gk@ninebynine.org>
Message-Id: <1068680859.13394.424.camel@dirk.dm93.org>

On Wed, 2003-11-12 at 17:13, pat hayes wrote:
> Guys, in the interests of full disclosure, here's a summary of the
> changes made to the semantics document in the last few days. I
> actually think that this is now *all*.

Hmm... no pointer to the text... using the one you've given
recently, I find...

$ HEAD http://www.ihmc.us/users/phayes/RDF_Semantics_LC2.5.html
200 OK
Date: Wed, 12 Nov 2003 23:36:40 GMT
ETag: "58d0c8-3b7ea-3fb28432"
Content-Length: 243690
Content-Type: text/html
Last-Modified: Wed, 12 Nov 2003 19:04:18 GMT

Hmm... I see the same text now that I saw when you said...

<patH> Dan, you still there?  The version now at
http://www.ihmc.us/users/phayes/RDF_Semantics_LC2.5.html  is completely
post-terHorst and has an updated changes log. You can run with that one
as far as Im concerned right now: thats my final Wednesday effort..

I checked it in at that point...

revision 1.46.2.6
date: 2003/11/12 19:15:48;  author: connolly;  state: Exp;  lines: +415
-365

That version doesn't become available at
  http://www.w3.org/TR/2003/WD-rdf-mt-20031010/
unless/until somebody merges that branch into the head.
Brian, feel free to do so.

Pat, does appendix D say pretty much what you're saying here?
Ah... I guess it does...

> 1. Section subheadings added/changed as per
> http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2003Nov/0051.html
> 
> 2. "name" now includes plain literals, so vocabularies (= sets of
> names) also may contain plain literals. They are not obliged to, so
> all old vocabularies are still new vocabularies.
> 
> 3. 'proper instance' now allows substitution of a plain literal for a
> bnode.
> 
> 4.  semantic conditions on simple interpretations of a vocabulary V
> are now restricted to the plain literals in V (as they were formerly
> for the URIs and typed literals. )
> 
> The effect of 2-4 is that all referring expressions (URIrefs and
> literals) are treated uniformly, and interpretations of a graph are
> only obliged to interpret the symbols which occur in the graph. All of
> this is conventional and makes the RDF MT more 'normal'. For
> justification of why it was needed, see Herman's recent comment on the
> failure of the RDFS entailment lemma proof
> http://lists.w3.org/Archives/Public/www-rdf-comments/2003OctDec/0150.html (see "To give an example, let A be a URI reference" et seq)
> No changes to any test cases or entailments arise.
> 
> 5.  minor editorial changes arising from 2-4 above, eg "name or plain
> literal" -> "name" in several places, and the example in figure 1 now
> has the literals listed in its vocabulary explicitly.
> 
> 6. Text added in 1.1 Technical note (Informative):
> "Readers who are familiar with conventional logical semantics may find
> it useful to think of RDF as a version of existential binary
> relational logic in which relations are first-class entities in the
> universe of quantification. Such a logic can be obtained by encoding
> the relational atom R(a,b) into a conventional logical syntax, using a
> notional three-place relation Triple(a,R,b); the basic semantic
> described here can be reconstructed from this intuition by defining
> the extension of y as the set {<x,z> : Triple(x,y,z)} and noting that
> this would be precisely the denotation of R in the conventional
> Tarskian model theory of the original form R(a,b) of the relational
> atom. This construction can also be traced in the semantics of the
> Lbase axiomatic description [LBASE]."

Is that supposed to fall under "Several pieces of explanatory prose have
been added, in response to requests for clarification."?

OK, I'll buy that.

> This point was raised by at least 3 people at ISWC and in other
> working groups, so I thought it might be worth drawing attention to.
> 
> 7. Other minor editorial suggested by Herman, eg "and A(E) is defined"
> added in the third semantic condition table. None of these change
> meanings, only clarify or correct errors.
> 
> 8. The definitions of the Hebrand interpretations in the proof
> appendix have been simplified somewhat, since they are no longer
> required to interpret all plain literals.  The definition of the 'sur'
> construction in the RDFS entailment lemma proof has been clarified;
> several explanatory paragraphs have been added to make the proofs
> easier to follow, and some typos corrected (which also helps, of
> course.) Again, for discussion and motivation see Herman's recent
> email comments.
> 
> 9. As well as the above, the change log notes the
> _:x rdf:type rdfs:ContainerMembershipProperty .
> empty entailment case discussed in earlier emails.

OK, good.

> Pat

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 12 November 2003 18:47:41 EST

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