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Issue 5.19 Classes-as-instances

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Fri, 18 Oct 2002 21:22:23 +0100
Message-ID: <3DB06D7F.2010205@hpl.hp.com>
To: www-webont-wg@w3.org


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 Friday, 18 October 2002 16:22:37 GMT

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