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Re: ISSUE-111 Proposal to Resolve

From: Jim Hendler <hendler@cs.rpi.edu>
Date: Mon, 18 Aug 2008 12:04:26 -0400
Cc: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>, public-owl-wg Group WG <public-owl-wg@w3.org>
Message-Id: <6AA356D5-162A-43A8-BCDF-19E29AB5FAA2@cs.rpi.edu>
To: Bijan Parsia <bparsia@cs.man.ac.uk>

Bijan,
  It is absolutely true as you say that if it is in OWL Full then it  
is in OWL Full (you said it better), but the key here is we're talking  
about when the user explicitly wants to signal that it should be OWL  
Full -- seems to me having a very specific thing, easy to find, in  
this particlar (and probably rare) case would make everyone's lives  
easier -- I don't understand the reluctance, I've looked at the  
discussion in the f2f, and it seems to mainly concern general issues  
with signaling intent, which I mostly agree with, the problem is this  
one specific case - and why can't we just have some little piece of  
syntax, which is only in OWL Full, which basically says "Don't expect  
complete/sound reasoning if you use me with an OWL DL tool" - seems to  
me we could do something more mnemonic that sameas Sameas sameAs --  
and would make things easier for both implementors and users
  Guess what I'm trying to ask is what would be the downside?  I can  
only see positive advantages as an implementor
  -JH


On Aug 18, 2008, at 10:48 AM, Bijan Parsia wrote:

>
> On 12 Aug 2008, at 13:10, Jim Hendler wrote:
>
>>
>> OK, so supposing I'm an OWL DL user and I want to use a DL  
>> reasoner.  I accidently, however, assert something that puts the  
>> ontology in Full (and when we did the analysis of 1500 ontologies 3  
>> years ago, there were at least 100 for which this case was true --  
>> usually because someone referred to something from a remote name  
>> space without adding the appropriate type or imported something  
>> that put them into Full without their realizing it) -- so according  
>> to this, tools like Pellet, instead of "fixing" these mistakes  
>> (heuristically) would now need to assume the person knew what they  
>> were doing and that they want to be in Full
>
> No. If an ontology is syntactically in OWL Full it is in OWL Full.  
> This has *always* been true.
>
> How to *handle* OWL Full ontologies remains, as it was then, up to  
> the tool. Pellet performs an analysis and repair phase with reports  
> back on the repairs performed and a strict mode. Nothing would  
> change with that.
>
>> -- so it would be rare that they want to do this on purpose, but  
>> not rare that it would happen by accident.
>> My point is not that I think there shoudln't be some way to do  
>> this, but rather that it should be explicit -- otherwise we get in  
>> a situation where tools will assume it's a mistake, and then the  
>> user will have to do something extra to make it clear they meant it
>> So my argument is not that we should have some way to always signal  
>> intended use, but that for this corner case, we should have  
>> something unambiguous that is not likely to be used by mistake  
>> (which is why, sameAs sameAs sameAs seems appealing)
>
> I think if we give advice and follow that advice up with tools  
> support (e.g., in the report say, "This ontology is OWL Full only in  
> virtue of the notorious sameAs^3 triple which generally means that  
> this is intended to be owl full. This reasoner does not support OWL  
> Full semantics, would you like the (sound but incomplete wrt  
> subusmption) OWL DL results anyway?"
>
> Cheers,
> Bijan.
>
>

"If we knew what we were doing, it wouldn't be called research, would  
it?." - Albert Einstein

Prof James Hendler				http://www.cs.rpi.edu/~hendler
Tetherless World Constellation Chair
Computer Science Dept
Rensselaer Polytechnic Institute, Troy NY 12180
Received on Monday, 18 August 2008 16:05:20 GMT

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