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Re: PRPOSAL to close ISSUE-8

From: Uli Sattler <sattler@cs.man.ac.uk>
Date: Thu, 13 Dec 2007 18:39:39 +0000
Message-Id: <5C737A6E-0EE1-4599-A995-562AD0C12154@cs.man.ac.uk>
Cc: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, public-owl-wg@w3.org
To: Alan Ruttenberg <alanruttenberg@gmail.com>


On 13 Dec 2007, at 18:31, Alan Ruttenberg wrote:

>
> On Dec 13, 2007, at 1:24 PM, Uli Sattler wrote:
>
>> On 13 Dec 2007, at 16:04, Alan Ruttenberg wrote:
>>
>>> I have had a discussion with Uli about this, and it seems that a  
>>> limited form of this would not compromise decidability - e.g. no  
>>> binary comparisons other than equality. She said she would write  
>>> up a proposal.
>>
>> ...I seem to remember that i agreed to have a think (!) about it
> Yes.
>> - and I had: it seems to me that (i) we would need to "fork" OWL11  
>> in a difficult to understand way (i.e., you can either use  
>> datatype properties at the end of property chains or, say,   
>> comparisons, but not both), and
>
> This doesn't seem in principal different than transitive properties  
> and cardinality constraints. Is it? If so, how would you  
> characterize the difference?

I partially agree (and thus partially disagree):  the difference  
seems to be the complexity of specifying conditions when you may or  
may not use properties in subproperty chains: it not only depends on  
subproperty axioms, but also on the usage of the datatype properties  
in comparisons...i am a bit short of time today and tomorrow, but i  
will continue thinking about it...

>
>> (ii) we would need to ask implementors whether they would be  
>> willing to implement this.
>
> Yes.
>
>> I would thus favour to not allowing them at all....Carsten?
>
> Yes, but we have two groups which clamor for them - Jim and Jeremy  
> representative of them, and they are kind of obviously useful.  
> Could we at least have the technical aspects of the case where they  
> are not used in comparisons laid out?
>
> Anyways, I think it would be useful to have that in front of us,   
> so we could have something concrete to ask the implementors about.
>
> -Alan
>
>>
>> Cheers, Uli
>>
>>> -Alan
>>>
>>> On Dec 13, 2007, at 9:56 AM, Peter F. Patel-Schneider wrote:
>>>
>>>>
>>>> Issue-8 asks for property chains that end with data properties.
>>>>
>>>> Adding this construct to OWL 1.1 would compromise decidability.
>>>> This feature would automatically be in an OWL Full version  
>>>> because in
>>>> OWL Full data properties are also object properties.
>>>>
>>>> Later discussion asked whether having data properties in the  
>>>> middle of
>>>> a chain can be done.
>>>>
>>>> In OWL 1.1 such chains would have an empty extension, and thus be
>>>> useless.  The situation in OWL Full is the same as for data  
>>>> properties
>>>> at the end of a chain.
>>>>
>>>> I therefore propose that we CLOSE ISSUE-8 (even though it is not  
>>>> even
>>>> OPEN) without doing anything on the twin grounds that it both
>>>> compromises decidability in OWL 1.1 and is not handled by tools,  
>>>> and
>>>> that there is nothing special that needs to be done in OWL Full.
>>>>
>>>> Peter F. Patel-Schneider
>>>> Bell Labs Research
>>>>
>>>> PS: I'm proposing handling ISSUE-8 in this manner as is it is  
>>>> closely
>>>>     related to ISSUE-83.
>>>>
>>>
>>>
>>
>
Received on Thursday, 13 December 2007 18:41:09 GMT

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