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Re: Some editorial comments (Re: ISSUE-131: Preview of "unification")

From: Jim Hendler <hendler@cs.rpi.edu>
Date: Mon, 25 Aug 2008 10:59:15 -0400
Cc: Ivan Herman <ivan@w3.org>, public-owl-wg Group WG <public-owl-wg@w3.org>
Message-Id: <CE70CDDF-B5A6-4BA9-AA29-6C4BD29FB75E@cs.rpi.edu>
To: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>

+1 to dropping the "2" from the profiles.
  -JH



On Aug 25, 2008, at 10:34 AM, Ian Horrocks wrote:

>
> On 25 Aug 2008, at 14:12, Ivan Herman wrote:
>
>> Hi Ian,
>>
>> first of all: thank you!
>>
>> I have some editorial issues/questions/comments on the profile  
>> document.
>> I may also have some more content questions at some point, but I  
>> thought
>> it would be better to get the editorial comments out of the way... So
>> here they are.
>>
>> - In the definition of OWL 2 EL, you refer to "satisfiability,
>> subsumption, classification, and instance checking" as being  
>> polynomial.
>> On the other hand, the introduction refers to "consistency,
>> classification, instance checking, and conjunctive query" as the
>> reasoning tasks used to describe the profiles. I think that the
>> introduction should describe all of those. Having said that: aren't
>> 'satisfiability' and 'consistency' the same, or am I missing the  
>> point?
>
> This clearly needs tidying up a bit and making more consistent  
> across the profiles. Consistency and satisfiability are often used  
> interchangably. I might be able to persuade myself that the  
> unqualified use of consistency usually refers to ontology  
> consistency (is there any model of the ontology as a whole) whereas  
> the unqualified use of satisfiability usually refers to classes (is  
> there a model of the ontology in which the interpretation of a given  
> class is non-empty). However, I think that it is better to  
> explicitly distinguish when we are talking about the ontology and  
> when we are talking about classes (e.g., ontology/class consistency).
>
>>
>> - In EL, bulleted item under 'The following features...', 2nd item,
>> there seem to be an extra ')' in the middle and an extra one at the  
>> end, too
>
> Fixed.
>
>>
>> - Section 3, introduction on QL, second paragraph refers to DL-Lite  
>> and
>> not QL, which is a bit out of the blue here (I suspect this is a
>> leftover). Actually, I wonder whether that paragraph should stay at  
>> all.
>
> I changed it to say that QL is based on a variant of DL-Lite. I  
> think this is useful as it allows us to explain the basis for QL, to  
> point to the literature and explain why this particular variant was  
> chosen.
>
>>
>> - Whereas the start up section of EL referred to the various  
>> reasoning
>> problems for which EL is well suited for, this is not so explicitly
>> stated for QL. I think it would be good to have a similar
>> characterization of QL, too; if _all_ reasoning problems are in
>> LOGSPACE, then it should be said explicitly.
>
> Good point. Some more work is needed on the introductory and  
> explanatory text throughout the document. It has lagged a bit behind  
> the others due to the "planning blight" caused by the possible  
> unification. Once this is resolved one way or the other we can get  
> on with this work.
>
>>
>> - Section 4, introducing OWL RL, I actually have the same comment as
>> before: it may be useful to be able to characterize (at least  
>> partially)
>> the profile with the reasoning problems. For example, isn't it  
>> correct
>> that the OWL 2 RL/RDF rules are not complete vs. classification but  
>> they
>> are vs. conjuctive query and instance checking, for example?
>
> I agree that we should be clearer about all this. Completeness  
> depends mainly on the structure of the ontology. If the ontology  
> satisfies the relevant syntactic conditions, then the rules are  
> complete for ground entailment. This means that they can also be  
> used for complete consistency checking (both class and ontology),  
> subsumption and classification. E.g., C is a subClassOf D just in  
> case asserting T(a rdf:type C) entails T(a rdf:type D) for some "a"  
> that is not mentioned elsewhere in the ontology. This is a standard  
> technique in rule based reasoning.
>
>
>>
>> (I think the reference to these reasoning tasks is a very good way of
>> comparing the various profiles, hence these remarks...)
>>
>> - I do not want to reopen the profile naming discussion too much,  
>> but:-(
>> Is it necessary to add the '2' to all profiles? I would have thought
>> that 'OWL QL', 'OWL RL', etc, would be o.k. It would also make the  
>> rule
>> representation a bit shorter: 'OWL RL/RDF' instead of 'OWL 2 RL/RDF'
>
> This would be fine for me -- there is no confusion because OWL 1  
> didn't have these profiles. If others agree, then changing the  
> document is a trivial task.
>
> Ian
>
>
>>
>> I guess that is for the moment after a first read through the text...
>>
>> Thanks
>>
>> Ivan
>>
>> Ian Horrocks wrote:
>>>
>>> We (Alan and I) agreed that it would help to clarify this issue  
>>> and to
>>> inform our discussion on Wednesday if the Profiles document [1] were
>>> updated to reflect the proposed "unification". This has now been  
>>> done.
>>> It should be read in conjunction with the (draft) conformance
>>> definitions [2].
>>>
>>> Regards,
>>> Ian
>>>
>>> [1] http://www.w3.org/2007/OWL/wiki/Profiles
>>> [2] http://www.w3.org/2007/OWL/wiki/Conformance
>>>
>>
>> -- 
>>
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>> FOAF: http://www.ivan-herman.net/foaf.rdf
>
>

"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, 25 August 2008 14:59:54 GMT

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