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Re: editorial tweak to OWL semantics doc

From: Jim Hendler <hendler@cs.umd.edu>
Date: Mon, 16 Dec 2002 18:20:19 -0500
Message-Id: <p05200f11ba240be87900@[129.2.179.23]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, phayes@ai.uwf.edu
Cc: horrocks@cs.man.ac.uk, www-webont-wg@w3.org

At 5:46 PM -0500 12/16/02, Peter F. Patel-Schneider wrote:
>From: pat hayes <phayes@ai.uwf.edu>
>Subject: Re: editorial tweak to OWL semantics doc
>Date: Mon, 16 Dec 2002 11:26:30 -0600
>
>>  >Hmm.
>>  >
>>  >Why shouldn't that go at the beginning of the RDFS-Compatible
>>  >Model-Theoretic Semantics section?  It appears to me that OWL/DL, when
>>  >written in N-triples,
>>
>>  Not N-triples; say RDF triples.
>
>Before I use the phrase ``RDF triple'' I would like to see a definition of
>them.  I looked in Concepts and Abstract Syntax and was highly
>underwhelmed.  ``An RDF triple contains three components, ....''  Sure, but
>just *what* is an RDF triple?  Is it a triple, in which case why are the
>components named?  Is it something else, like a data structure, in which
>case just what sort of data structure is it?
>
>I am unwilling to say that the (abstract) syntax of OWL contains elements
>that can be *anything*.  How are these sorts of thing supposed to be
>represented?
>
>So, unless there is a *decision* of the working group, I am not going to
>use RDF triples until their definition is cleaned up or at least until I
>can understand just what is going on.
>
>peter


Peter - the decision of the WG was that RDF/XML was our normative 
transfer syntax, and that the RDF Graph conveyed the semantics.  I 
think you have some leeway within those to make editorial decisions, 
but the WG has already made certain decisions with respect to this.


With respect to your question as to what the triples consist of, 
might I suggest that [1]

>  The RDF Graph has Nodes and labeled directed Arcs that link pairs 
>of Nodes and this is represented as a set of RDF triples where each 
>triple contains a Subject Node, Property Arc and Object Node. Nodes 
>are RDF URI References, RDF Literals or are Blank Nodes and for 
>encoding in syntaxes may be given a document-local, non-RDF URI 
>References identifier called a Blank Node Identifier. Arcs are 
>labeled with RDF URI References. The property arc can be interpreted 
>as either a relationship between two nodes or as defining an 
>attribute value (object node) for some subject node.

seems to contain what you are asking for, and that the Concept and 
Abstract has more than you cite - you seem to have missed [2] which 
has some more detail, and you only quote part of [3] which contains a 
definition of graph equality for RDF graphs as well.

I also find it odd that you prefer N-triples, which seem to only have 
normative status in the RDF test document where they are defined 
purely syntactically in [4] and the  semantics offered for them are a 
pointer to the cwm document [5].

[1] http://www.w3.org/TR/2002/WD-rdf-syntax-grammar-20021108/
[2] http://www.w3.org/TR/rdf-concepts/#xtocid48021
[3] http://www.w3.org/TR/rdf-concepts/#section-Graph-syntax
[4] http://www.w3.org/TR/rdf-testcases/#ntriples
[5] http://www.w3.org/TR/rdf-testcases/#n3
-- 
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
Received on Monday, 16 December 2002 18:21:32 GMT

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