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Re: declaredAs

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Tue, 14 Aug 2007 12:22:09 +0100
Message-Id: <B88A7CBC-A76D-418D-8CD1-15CEA901B84B@cs.man.ac.uk>
Cc: public-owl-dev@w3.org
To: "Turner, David" <davidt@hp.com>

On 14 Aug 2007, at 11:52, Turner, David wrote:

>> -----Original Message-----
>> From: public-owl-dev-request@w3.org
>> [mailto:public-owl-dev-request@w3.org] On Behalf Of Pat Hayes
>> Sent: 09 August 2007 17:24
>> Subject: Re: declaredAs
>>
>>> Thus the WG will take OWL 1.1 as an input, but, presumably, work to
>>> flesh out other OWL Full aspects (punning is, in fact, a
>> move in this
>>> direction).
>>
>> Not really. Im sure it was meant to have this intention, but
>> the effect of moving to punning is two-fold: it breaks the
>> OWL Full semantics, and it breaks the semantic connection
>> between OWL and RDF.
>
> I realise that this point has been elaborated on later in this thread,
> but I wanted to express my general agreement with it anyway.  
> Punning is
> rather different from what OWL Full does,

I don't know what you mean by "rather different". For me, for  
example, "rather different" suggests *incompatibility*. Punning is,  
as far as I know, strictly weaker than Hilog or OWL Full semantics.  
Thus a reasoner that only respects the punning semantics will be  
sound but incomplete with respect to the OWL Full semantics. They, in  
fact, coincide in the absence of equality.

> and you can observe this
> difference via owl:sameAs:
>
> ex:A owl:disjointWith ex:B .
> ex:A owl:sameAs ex:B .
> _:x rdf:type ex:A .

Yeah, this was bandied about before in some form or another. I mean,  
it doesn't really add anything over the observation that, under Hilog  
semantics, if A=B then A iff B. (After all, A iff B means A & ~B is  
unsatisfiable, and thus x:(A & ~B) is inconsistent....let's not get  
distracted by irrelevant bits.)

> is syntactically invalid in OWL-1.0 DL, inconsistent in OWL-1.0  
> Full and
> consistent in OWL-1.1 with punning (with thanks to Dave Reynolds)

There are many graphs that are consistent in under simple  
interpretations and inconsistent under RDFS semanatics. So either  
this sort of being rather different is relatively innocuous (at least  
ceteris paribus), or there's something else that distinguishes them.  
I don't know what that something else could be, so would welcome  
clarification.

Cheers,
Bijan.
Received on Tuesday, 14 August 2007 11:21:10 GMT

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