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Re: Issue 5.19 Classes-as-instances

From: Jos De_Roo <jos.deroo.jd@belgium.agfa.com>
Date: Tue, 22 Oct 2002 15:03:55 +0200
To: "Jeremy Carroll <jjc" <jjc@hplb.hpl.hp.com>
Cc: www-webont-wg@w3.org, www-webont-wg-request@w3.org
Message-ID: <OF34D2CB2B.D1340503-ONC1256C5A.0046AA9D-C1256C5A.0047C54F@agfa.be>


I believe we should talk about namespace entailment
(ako premise) and for the moment we have
  simple entailment
  <http://www.w3.org/2000/01/rdf-schema> entailment
  <http://www.w3.org/2002/07/owl> entailment
so unless we have other namespaces, owl-entailment
seems B&W to me (and your example holds)

-- ,
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/


                                                                                                                       
                    Jeremy Carroll                                                                                     
                    <jjc@hplb.hpl.hp.c       To:     www-webont-wg@w3.org                                              
                    om>                      cc:                                                                       
                    Sent by:                 Subject:     Issue 5.19 Classes-as-instances                              
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                    est@w3.org                                                                                         
                                                                                                                       
                                                                                                                       
                    2002-10-18 10:22                                                                                   
                    PM                                                                                                 
                                                                                                                       
                                                                                                                       






Many months ago Ian asked the very good question what difference does this
make?

Here is an entailment:


Description: (informative)

If two URIrefs denote the same thing, then their class extensions are also
the same.


premises
========

first:thing owl:sameInstanceAs first:sameThing .

conclusions
===========

first:thing owl:sameClassAs first:sameThing .


++++++++++++++++++++++++++


My understanding of the current consensus (being challenged by Enrico) is.

This entailment holds in Large OWL.
In Fast OWL and Lite OWL it is (syntactically?) problematic, because it
does not satisfy the separation of classes from things condition.

Thus, this test case should be added to the test document with the test
editors instructed to clarify that this:
+ is a valid large owl entailment
+ should not be expected from a fast owl or owl lite system
+ that a fast owl or owl lite system may indicate that there is an
ill-formedness in the question
+ that a fast owl or owl lite system may find this entailment

And even for a large owl system, one should remember that large owl
reasoners will be incomplete!

I suspect with some care the Test document could support a range of
conformance options indicated by metadata tags on the tests ....

So I am suggesting rephrasing the classes as instances problem into what
sort of behaviour do we expect systems to show with this entailment; and
how do we document these expectations.

Jeremy
Received on Tuesday, 22 October 2002 09:05:40 GMT

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