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RE: [OWLWG-COMMENT] Re: Cardinality Restrictions and Punning

From: Pat Hayes <phayes@ihmc.us>
Date: Sat, 5 Jan 2008 19:34:58 -0800
Message-Id: <p0623090dc3a5f7762bc9@[]>
To: "Michael Schneider" <schneid@fzi.de>
Cc: "Evren Sirin" <evren@clarkparsia.com>, "Owl Dev" <public-owl-dev@w3.org>

>>  On 11/2/07 3:23 PM, Michael Schneider wrote:
>>>  Hi, Evren!
>>>  Evren Sirin wrote on November 02, 2007:
>>>>  Michael,
>>>>  You are correct in your understanding of punning. It is true that
>>>>  punning semantics is strictly weaker than OWL-Full semantics and the
>>>>  inferences you will get will be a subset of OWL Full entailments.
>Is this a certain fact? I remember to have heard this claim a few times
>before now, but don't remember to have ever heard about evidence for it.
>Since there is no 1.1-Full draft at the moment, is there some proof that
>this would be true for 1.0-DL+Punning in comparison to 1.0-Full?

Yes, because in the Full semantics, :sameAs 
entails :equivalentClass, but not in the punning 
semantics. It is easy to construct many examples 
based on this which illustrate the disconnect 
between punning and the RDF/hilog style semantics.

One way to minimize (although not completely 
eliminate) these issues would be to redefine what 
'sameAs' means in 1.1.  1.0:sameAs really does 
mean equality. In 1.1, however, it no longer 
means that, as it is restricted to individuals. 
If this were altered so that 1.1:sameAs means 
equality for all the name categories, i.e. if it 
was the conjunction of DL-sameAs, equivalentClass 
and equivalentProperty, then most entailments 
would carry over from the 1.0 case to the 1.1 
case. This would require introducing a new 'weak' 
identity for individuals, call this sameThingAs 
(just for now), then sameAs means the same thing 
in 1.0-Full and 1.1-Full, and 1.0-DL:sameAs means 
the same as 1.1-DL:sameThingAs; but since 
1.1:sameAs when restricted to individuals means 
1.1:sameThingAs, and since 1.0 only allows sameAs 
to be used between individuals, all 1.0 DL 
ontologies should retain their meanings in 1.1-DL 
also. The only case that would need care when 
moving from 1.0 to 1.1 is taking an existing 
1.0-DL ontology and extending it using punning to 
be 1.1-DL legal but not 1.0-DL-legal. In this 
case, the 1.0-sameAs statements need to be 
restricted (I presume: Im not an expert on the 
logistics of punning) to the individual case, 
which in this suggested scenario would require 
changing the ontology by replacing sameAs by 
sameThingAs. This might be considered a 
dealbreaker, but I think the idea is worth 
careful consideration, as it is semantically more 
correct and makes the overall DL/Full 
relationship in 1.1 much less confusing. (And how 
many published OWL ontologies actually use sameAs 
in ways that are remotely likely to be confused 
by subsequent punning extensions?)

Anyway, though I would put this on the table for discussion.


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Received on Sunday, 6 January 2008 03:35:14 UTC

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