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Re: Proposed response to Golbeck regarding imports issue

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Tue, 17 Jun 2003 14:29:11 +0100
Message-ID: <16111.6055.386614.505868@merlin.horrocks.net>
To: Jim Hendler <hendler@cs.umd.edu>
Cc: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, www-webont-wg@w3.org

Jim,

Quoting from Test:

    An OWL Lite or OWL DL document D is consistent with respect to a
    datatype theory T if and only if there is some abstract OWL
    interpretation I with respect to T such that I satisfies an
    abstract ontology O equivalent to D, in which O has a separated
    vocabulary; (see [OWL Semantics and Abstract Syntax]).

    An OWL Full document D is consistent with respect to a datatype
    theory T, if and only if there is some OWL Full interpretation I
    with respect to T such that I satisfies all the RDF graphs in some
    imports closed collection containing an RDF graph equivalent to D.

    ...

    An OWL consistency checker MUST be sound: it MUST return
    Consistent only when the input document is consistent and
    Inconsistent only when the input document is not consistent, with
    respect to the datatype theory of the checker.


A document containing only the assertion that x is of type
http://...foo#bar is clearly consistent according to the above
specification, regardless of the contents of http://...foo. If you
have a consistency checker that imports the contents of http://...foo
and returns "Inconsistent" if this leads to an inconsistency, then
your consistency checker is unsound according to the spec.


If you would like to have a tool that does some automatic importing,
then the obvious solution is to have it automatically extend the
ontology with the required import statements. Using this kind of tool
along with the existing imports statement lets everyone do more or
less what they want to do - you and Dan can do different kinds of
automatic importing, and others can do only explicit importing.

Ian






On June 17, Jim Hendler writes:
> At 11:53 PM -0400 6/16/03, Peter F. Patel-Schneider wrote:
> 
> >If there is not an imports statement, then OWL does not license importing.
> >Any software that does so is not fully OWL compliant.  The negative
> >entailment test Imports-002 is a test of this situation.
> >
> >
> >peter
> 
> 
> Peter - negative entailment test002 reads:
> 
> If a premise document uses a namespace but does not import the 
> document corresponding to the namespace, then the premises do not 
> necessarily entail anything that is entailed by the conjunction of 
> the two documents.
> 
> 
> "The premises do not necessarily entail" which is not the same as 
> saying the premises necessarily do not entail.
> 
> Further, the definition of a non-entailment test is:
> 
> 3.3. Non-Entailment Tests These tests use two documents. One is named 
> premisesNNN.rdf, the other is named nonconclusionsNNN.rdf. The 
> nonconclusions are not entailed by the premises. Such entailment is 
> defined by the OWL semantics [OWL Semantics and Abstract Syntax], 
> (see also OWL Full entailment). Exceptionally, test imports-002 
> includes a third document.
> 
> 
> i.e. not entailed by, which I believe is not the same as "the 
> negation is entailed by"
> 
> 
> I read this one carefully before I was willing to approve it, and 
> this statement is, indeed, consistent with the decision taken by the 
> group.
> Our normative test document is therefore consistent with what I 
> described yesterday and I believe this still stands.
> 
>   -JH
> 
> 
> -- 
> 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	  *** 240-277-3388 (Cell)
> http://www.cs.umd.edu/users/hendler      *** NOTE CHANGED CELL NUMBER ***<!doctype html public "-//W3C//DTD W3 HTML//EN">
> <html><head><style type="text/css"><!--
> blockquote, dl, ul, ol, li { padding-top: 0 ; padding-bottom: 0 }
>  --></style><title>Re: Proposed response to Golbeck regarding imports
> iss</title></head><body>
> <div>At 11:53 PM -0400 6/16/03, Peter F. Patel-Schneider wrote:</div>
> <div><br></div>
> <div>&gt;If there is not an imports statement, then OWL does not
> license importing.<br>
> &gt;Any software that does so is not fully OWL compliant.&nbsp; The
> negative</div>
> <div>&gt;entailment test Imports-002 is a test of this situation.<br>
> &gt;</div>
> <div>&gt;</div>
> <div>&gt;peter</div>
> <div><br></div>
> <div><br></div>
> <div>Peter - negative entailment test002 reads:</div>
> <div><br></div>
> <div>If a premise document uses a namespace but does not import the
> document corresponding to the namespace, then the premises do not
> necessarily entail anything that is entailed by the conjunction of the
> two documents.</div>
> <div><br></div>
> <div><br></div>
> <div>&quot;The premises do not necessarily entail&quot; which is not
> the same as saying the premises necessarily do not entail.</div>
> <div><br></div>
> <div>Further, the definition of a non-entailment test is:</div>
> <div><br></div>
> <div>3.3. Non-Entailment Tests These tests use two documents. One is
> named premisesNNN.rdf, the other is named nonconclusionsNNN.rdf. The
> nonconclusions are not entailed by the premises. Such entailment is
> defined by the OWL semantics [OWL Semantics and Abstract Syntax], (see
> also OWL Full entailment). Exceptionally, test imports-002 includes a
> third document.</div>
> <div><br></div>
> <div><br></div>
> <div>i.e. not entailed by, which I believe is not the same as
> &quot;the negation is entailed by&quot;</div>
> <div><br></div>
> <div><br></div>
> <div>I read this one carefully before I was willing to approve it, and
> this statement is, indeed, consistent with the decision taken by the
> group.</div>
> <div>Our normative test document is therefore consistent with what I
> described yesterday and I believe this still stands.</div>
> <div>&nbsp;</div>
> <div>&nbsp;-JH</div>
> <div><br></div>
> <div><br></div>
> <x-sigsep><pre>-- 
> </pre></x-sigsep>
> <div>Professor James Hendler<x-tab>
> </x-tab><x-tab>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
> </x-tab><x-tab>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
> </x-tab><x-tab>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </x-tab>&nbsp;
> hendler@cs.umd.edu<br>
> Director, Semantic Web and Agent
> Technologies<x-tab>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </x-tab>&nbsp;
> 301-405-2696<br>
> Maryland Information and Network Dynamics Lab.<x-tab>&nbsp;&nbsp;&nbsp;
> </x-tab>&nbsp; 301-405-6707 (Fax)<br>
> Univ of Maryland, College Park, MD 20742<x-tab>&nbsp;&nbsp;&nbsp;
> </x-tab>&nbsp; *** 240-277-3388 (Cell)<br>
> http://www.cs.umd.edu/users/hendler&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ***
> NOTE CHANGED CELL NUMBER ***</div>
> </body>
> </html>
Received on Tuesday, 17 June 2003 09:29:47 GMT

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