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Re: issues to be resolved before last call

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 21 Jan 2003 17:13:36 -0500 (EST)
Message-Id: <20030121.171336.05465629.pfps@research.bell-labs.com>
To: hendler@cs.umd.edu
Cc: www-webont-wg@w3.org

From: Jim Hendler <hendler@cs.umd.edu>
Subject: Re: issues to be resolved before last call
Date: Mon, 20 Jan 2003 12:31:14 -0500

> I have read all the emails in this thread as of Jan 20 (noon EST) - I 
> return to Peter's original email because I think we need to make sure 
> we don't lose track of these issues w/respect to WG practice.
> 
> Please note: in this case I am writing as CHAIR - the below is how I 
> as chair would prefer to handle these issues based on the discussion 
> - they do NOT reflect my personal opinions with respect to resolving 
> the issues
> 
> Also note that these are NOT chair rulings, as I have not discussed 
> them with Guus and Dan - consider this a set of suggestions:
> 
> 
> 
> 
> At 7:44 -0500 1/17/03, Peter F. Patel-Schneider wrote:
> >		Technical Issues to be resolved before last call
> >
> >
> >Here are some issues that I feel must be resolved before OWL goes to last
> >call.  I have battled to get the RDF issues resoved, but to little
> >success.  I would like to have formal votes on all the proposed resolutions
> >herein.
> >
> >
> >
> >Issues with XML Schema:
> >
> >1/ The value spaces of xsd:decimal and xsd:float are not disjoint.  Right
> >    now in both XSD datatyped RDF and OWL the denotation "234.5"^^xsd:float
> >    is an element of the class extension of the denotation of xsd:decimal.
> >
> >    PROPOSED RESOLUTION:  The class extensions of xsd:decimal and xsd:float
> >    are not disjoint.   The class extension of xsd:float is a subset of the
> >    class extension of xsd:double.
> 
> I do not believe it is appropriate for OWL to have our own decision 
> on this without very strong justification.  The W3C Semantic Web 
> Coordination Group has asked RDF Core to discuss these issues with 
> the XML Schema folks.  I don't think it makes sense for us to have a 
> non-interoperable use of xsd types between OWL and other W3C specs.

The issue does not arise in XML Schema datatypes.  Therefore they have not
answered the question.  The issue does arise in OWL (and
XSD-interpretations in RDF).  Moreover, there are observable consequences,
in both OWL and RDF.

How can the WebOnt WG proceed without an answer to this question?


> >Issues with RDF Concepts:
> >
> >1/ The notion of social meaning has no place in the specification of a
> >    formal system.
> >
> >    PROPOSED RESOLUTION:  Social meaning, as defined in the RDF Concepts
> >    document, has no effect whatsoever on the meaning of OWL ontologies.
> >
> >    NB:  I view this as an extremely serious issue.
> 
> this is obviously getting most of the discussion, I will send a 
> separate message about this - my basic suggestion is that it does not 
> need an explicit action by our WG at the time.

Well, I consider this an impediment to further progress in the WG.

> >Issues with the RDF model theory:
> 
> (snips between the following)
> >
> >
> >1/ The class extension of rdfs:Literal does not necessarily include
> >    strings.  Right now, "a" rdf:type rdfs:Literal . is not RDFS-entailed by
> >    the empty graph.  Also, without the following fix, "a" rdfs:type _:x
> >    . _:x owl:complementOf rdfs:Literal . is not OWL Full entailed by the
> >    empty graph.
> >2/ XSD-interpretations in RDF include the problematic XML Schema
> >    datatypes.
> >3/ There is no definition of literal strings or language tags in the RDF
> >    Schema document.
> >4/ There is contradictory and unclear information with respect to what is a
> >    datatype as well as to the treatment of typed literals.  Datatypes are
> >    sometimes elements of the semantic domain, denoted by URI references,
> >    and sometimes the URI references themselves.  There is no necessary
> >    connection between the intended URI reference for a datatype and the
> >    datatype itself.
> 
> [snip]
> 
> The RDF Core WG has voted to go to Last Call with their documents, 
> including Semantics.  I believe at this point most of the issues 
> Peter raises can be resolved between Pat and Peter - the editors of 
> RDF Core's Semantics and ours.  Where they can work these out as 
> editing changes to RDF Semantics, it seems to me that is preferred. 

I've been trying to get these issues resolved to no avail.  I believe that
there needs to be substantive (i.e., non-editorial) changes to the RDF
Semantics document before RDF is suitable as a basis for OWL.

> If there are issues that still remain, our WG can decide whether to 
> send a WG comment to RDF Core's LC suggesting changes, or we can 
> decide to fix our documents.  The "editorial change" solution is 
> easiest for both WGs, of course we need to make sure things work out. 
> I would suggest we delegate Peter to discuss this with Pat off line 
> and come back with a specific solution.

I've been trying to do this for quite some time.  As RDF Core has voted to
go to LC status with many outstanding comments from me, I don't see what
further can be done.

> >  5/ The non-normative parts of the RDF model theory, including the closure
>     rules and the translation to Lbase, have many errors.
> [snip]
> 
> this one in particular should be fixed by editing - for us to declare 
> the RDF Core semantics to be non-normative would be odd in the 
> extreme, and likely to backfire badly as the RDF Core documents are 
> likely to be approved while ours are still in Last Call.  Sniping 
> between the two groups would be silly - we should be working together 
> to fix things, not to create friction.

Yes, agreed, but it takes two participants to work together, and very
little was happening on the RDF Core WG side.  

Note that I am not proposing that WebOnt treat RDF Semantics as
non-normative, just that WebOnt treat the non-normative sections of the RDF
Semantics as providing no guidance.

> Professor James Hendler				  hendler@cs.umd.edu
> 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	  240-731-3822 (Cell)
> http://www.cs.umd.edu/users/hendler

peter
Received on Tuesday, 21 January 2003 17:13:46 GMT

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