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Re: [closed] pfps-05 RDFS Closure Rules

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 21 Apr 2003 23:38:28 -0400 (EDT)
Message-Id: <20030421.233828.60032127.pfps@research.bell-labs.com>
To: phayes@ai.uwf.edu
Cc: www-rdf-comments@w3.org

From: pat hayes <phayes@ai.uwf.edu>
Subject: [closed] pfps-05 RDFS Closure Rules
Date: Mon, 21 Apr 2003 18:27:55 -0500

> Peter,
> Re. your comment
> http://lists.w3.org/Archives/Public/www-rdf-comments/2003JanMar/0090.html
> The editor has accepted your comment and the closure rules have been 
> modified to cover this (and other ) cases, by incorporating 
> existential generalization as an explicit closure rule.
> Please reply to this email, copying www-rdf-comments@w3.org indicating
> whether this decision is acceptable.
> Pat

This decision is not acceptable. 

It is not acceptable for structural reasons.  

First, no indication of the changes that have been made are accessible from
this message.  Second, the comment was not just about existential closures,
but instead was about whether the closure procedure for RDFS are complete and
whether the RDFS entailment lemma is true.  The response above does not
address this portion of my comment.

My investigations of the current editor's draft of RDF Semantics (21a) also
indicate that there remain in this draft problems related to my comment.

First, the semantic conditions for RDFS uses IC(rdfs:Container), which is
ill-defined.  If this is changed to the meaningful ICEXT(rdfs:Container),
the condition is not appropriate.  Even if this is changed from a range to
a domain, I believe that it is still not appropriate because I believe that
the intent in RDFS is that container membership properties can be applied
to non-containers.

Second, the RDFS closure procedure says to add the triples from a table and
some other triples.  However, these other triples are already in the table.

Third, the closure rules are unable to infer any rdfs:domain or rdfs:range
triples.  It thus appears to me that the RDFS closure procedure is still
incomplete as it will not include triples of the form

	rdf:_n rdfs:range xx .

(for whatever xx is deemed to be appropriate).

I note also that there are many changes to the RDF Semantics.  These
changes may have uncovered previously unnoticed issues and may themselves
have issues.

Received on Monday, 21 April 2003 23:38:37 UTC

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