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significant problem for moving OWL to Last Call

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 27 Mar 2003 09:49:47 -0500 (EST)
Message-Id: <20030327.094947.92619735.pfps@research.bell-labs.com>
To: herman.ter.horst@philips.com
Cc: www-webont-wg@w3.org

Herman ter Horst just brought to my attention a significant change to the
RDFS semantics in the editor's version of the RDF semantics document.  

This change involves adding new constructs to the definition of RDFS
interpretations as follows:

 	An rdfs-interpretation of V is an rdf-interpretation 
	I of (V union rdfV union rdfsV) *with a distinguished subset IC 
	of the universe and a mapping ICEXT from IC to the set of 
	subsets of IR*, which satisfies the following semantic 
	conditions and all the triples in the subsequent table, 
	called the RDFS axiomatic triples.  [Emphasis added]

Previously RDFS interpretations used the same structure as RDF
interpretations, and IC and ICEXT were conveniences only.

To track this change will require significant changes to S&AS.  I do not
feel that OWL can go to last call without some resolution of this new
issue.

Peter F. Patel-Schneider
Bell Labs Research
Lucent Technologies

PS:  If I had my druthers, I would change RDFS interpretations back to
being just like RDF interpretations as they were in the Last Call version
of the RDF semantics.  If a clarification is needed I would proceed
somewhat along the lines of defining rdfs-interpretations as

 	An rdfs-interpretation of V is an rdf-interpretation I of (V union
	rdfV union rdfsV) which satisfies the following semantic conditions
	and all the triples in the subsequent table, called the RDFS
	axiomatic triples.  For convenience, and to make the semantic
	conditions easier to understand, ICEXT is defined as
		ICEXT(x) = { y | <y,x> is in IEXT(I(rdf:type)) }
	and IC is defined as
		IC = { y | <y,I(rdfs:Class)> is in IEXT(I(rdf:type)) }
	which is the same as saying
		IC = ICEXT(I(rdfs:Class))

and then removing the second semantic condition.  I would also remove the
discussion of IC and ICEXT before the definition of an rdfs-interpretation,
but not the discussion of a class, although minor changes would need to be
made there.

PPS:  Someone in the RDF Core WG may want to forward this message to the WG.
Received on Thursday, 27 March 2003 09:49:57 GMT

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