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Re: Changes to make S&AS consistent with RDF Semantics document

From: Jim Hendler <hendler@cs.umd.edu>
Date: Tue, 2 Dec 2003 09:13:23 -0500
Message-Id: <p05200f3bbbf24d9c19da@[]>
To: herman.ter.horst@philips.com, horrocks@cs.man.ac.uk
Cc: www-webont-wg@w3.org

  I believe Ian is still finishing this up - however, let me remind 
you as chair that we all agreed that your comments would be sent to 
the editors for their decisions -- there is no promise that every one 
of these will be addressed in exactly the way you want.  Fastest, of 
course, might be for you to talk directly to Ian and discuss
p.s. Peter remains a document editor, I hope you are cc'ing your 
emails to him and, if he has time and the inclination, he can work 
with Ian to resolve them -- as we've discussed document editors don't 
have to be WG members (however, we have less claim on the time of 
non-WG members, so it is really at Peter's discretion to participate 
as much or as little as he can manage)

At 12:00 PM +0100 12/2/03, herman.ter.horst@philips.com wrote:
>Most of the comments I made in [1] are reflected in the
>current editors's draft.
>Four comments are not yet dealt with:
>>- In Section 5.2, it should be said that an OWL interpretation,
>>and also an OWL Full interpretation and an OWL DL interpretation,
>>are defined with respect to a datatype map D.
>>The same is true for OWL Full entailment and OWL DL entailment.
>>This is also made explicit in this way for abstract OWL
>>interpretations and abstract OWL entailment in Section 3.
>>Also, the statement of the correspondence theorem needs to be made
>>more explicit in this way.
>(Section 3.1: second bulleted condition:)
>>-It is now assumed that LV contains each Unicode string
>>and each pair of two Unicode strings.
>>For the correspondence with Section 5, it would be
>>sufficient to assume only that plain literals in
>>V (and L) are contained in LV.
>On further reflection, it seems that not only the assumption
>about plain literals but also the assumption about
>typed literals could be weakened.
>The condition could be rephrased, for example, as follows:
>"LV, the literal values of I, is a subset of R that
>contains the values of plain literals in V, and,
>for each datatype d in D and well-typed literal
>"v"^^d in V, the value L2V(d)(v)."
>It seems that this assumption would suffice for
>all the normative text in S&AS.
>A motivation to make this change is that similar
>unneccesary assumptions in the RDF Semantics led
>to many complications and the need for a similar
>>-In order to make the definition more strongly parallel
>>to the definition of ill-typed literals (and datatype
>>clash) in the RDF Semantics document, it seems to be better
>>to replace, in the last bulleted condition,
>>    R-V(d)
>>    R-LV
>>  ... many of the changes I describe here lead to the need
>>  for corresponding changes in the proof appendix.
>The proof appendix is not yet up to date with the changes
>One comment needs to be added to those in [1]:
>Both S&AS and RDF Semantics define datatype maps
>to be partial maps from URI references to datatypes.
>RDF Semantics assumes, in addition, that each datatype
>map contains rdf:XMLLiteral.
>S&AS assumes, in addition, that each datatype map
>contains xsd:string and xsd:integer.
>S&AS could be made consistent with RDF Semantics
>by correcting the third definition in Section 3.1
>in for example the following way:
>"As in RDF, a datatype map D is a partial mapping from
>URI references to datatypes that maps rdf:XMLLiteral
>to the built-in XML Literal datatype defined in the
>RDF Concepts and Abstract Syntax document [RDF Concepts].
>In addition, it is assumed that datatype maps
>map xsd:string and xsd:integer to the appropriate
>XML Schema datatypes."
>A corresponding addition to the first definition in
>Section 5.2 would then be needed.
>It should be noted that if XMLLiteral is not added
>by default to each datatype map, as in the RDF Semantics,
>document, then S&AS seems to be inconsistent.
>To see this, consider the following example:
>RDF graph G, just two triples
>   v p l
>   p rdfs:range rdfs:Literal
>where l is an ill-typed XML literal.
>Since G has no rdfs-interpretations, it has no D-interpretations
>for any datatype map D, and also no OWL DL interpretations
>for any datatype map D, so G is OWL DL inconsistent.
>Abstract syntax ontology O, containing
>   Individual(v value(p l))
>   DataProperty(p range(rdfs:Literal))
>If D is a datatype map that does not contain rdf:XMLLiteral,
>then O is consistent.
>It is clear that the translation of O with the mapping T of
>S&AS contains the RDF graph G.
>This contradicts the corollary to Theorem 1 in Section 5.4
>in S&AS, for any datatype map D that does not contain
>(I am using here my first comment above, that Theorem 1 etc.
>should be read as holding for a certain datatype map.)
>[1]  http://lists.w3.org/Archives/Public/www-webont-wg/2003Nov/0132.html

Professor James Hendler			  http://www.cs.umd.edu/users/hendler
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  240-277-3388 (Cell)
Received on Tuesday, 2 December 2003 09:13:24 UTC

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