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Re: OWL Full proposal (sort of) - addressing my Action

From: Jim Hendler <hendler@cs.rpi.edu>
Date: Tue, 12 Feb 2008 14:00:55 -0500
Cc: Jeremy Carroll <jjc@hpl.hp.com>, "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>
Message-Id: <446740E8-99B8-430D-A47D-414BE6277E13@cs.rpi.edu>
To: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>

I'd be fine with this - but just to be clear, we're talking about  
documenting OWL 1.1 Full here, not DL which, as I understand it, is  
not yet under development - apologies if I've missed something from a  
recent UFDTF decision.
  -JH


On Feb 12, 2008, at 1:09 PM, Ian Horrocks wrote:

>
> I share Jeremy's desire to maintain a significant degree of rigour  
> w.r.t. OWL Full; in fact I would say the same for all species/ 
> fragments/conformance-levels. Moreover, from what Jim says in emails  
> such as [1] it would seem that he has no objection to this and  
> perhaps even believes it to be mandatory. Instead, what he seems to  
> be asking for (in [1] at least) is a more human readable explanation  
> for those who find model theories difficult to understand. I don't  
> see any problem with that -- in fact we already have a commitment to  
> producing such documents and even a UFDTF busily engaged in their  
> development. So, if we were to agree to produce a "delta to OWL-1.0- 
> Full" as outlined by Michael in [2] plus suitable documentation for  
> the MT-challenged, would this satisfy everyone's requirements?
>
> Ian
>
> [1] http://lists.w3.org/Archives/Public/public-owl-wg/2008Feb/ 
> 0069.html
> [2] http://lists.w3.org/Archives/Public/public-owl-wg/2008Feb/ 
> 0068.html
>
>
> On 11 Feb 2008, at 09:05, Jeremy Carroll wrote:
>
>>
>>
>> I found Peter's clarification of the semantic options helpful;  
>> perhaps in allowing me to understand why I was uncomfortable with  
>> Jim's proposal.
>>
>> Jim seems to be suggesting something inbetween Peter's "D/  
>> Informal" and his "C/ Operational".
>> I fear we would find a long term loss in interoperability, for a  
>> short term gain in ease of reaching a design.
>>
>> I note that any of Peter's A/ Model theory E/ Transformational or  
>> F/ Axiomatic can give the same level of rigour and, since we start  
>> with model theoretic approaches we may as well continue with them,  
>> if we want this level of rigour.
>>
>> Jim appears to not want that.
>>
>> ===
>>
>> I do want to maintain significant degree of rigour with the  
>> definition of OWL Full for a variety of reasons.
>>
>> 1) Architectural
>>
>> My understanding of the Semantic Web is that the semantics is  
>> attached to the RDF graph, and different layers can *add*  
>> additional semantics to a graph by means of providing semantic  
>> extensions (and/or definitions of classes and properties in terms  
>> of ontology languages such as RDFS and OWL).
>> Since these semantics are additions within a strict monotonic  
>> paradigm, a certain degree of interoperation is provided.
>>
>> There are a variety of errors in the history of RDF prior to the  
>> introduction of the RDF Semantics (e.g. containers and  
>> reification), where an informal and partially operational semantics  
>> results in systems that do not have such well behaved semantics and  
>> have unpredictable behaviour.
>>
>> So the model theoretic semantics provides a discipline against error.
>>
>> 2) Minimize change
>>
>> I personally see OWL 1.1 as a small change on OWL 1.0. The two key  
>> changes I believe are QCRs and subproperty chains.
>>
>> I am less than happy with almost any change over and above these,  
>> other than minor corrections.
>>
>> 3) Product positioning
>>
>> I don't see HP's OWL Full offering as a "scruff's only" deal (in  
>> the old AI scruffs v neats debate).
>> I see the choice of whether to use OWL (for both Full or DL) in a  
>> scruffy or neat fashion as an end-user decision.
>> The choice of Full or DL is primarily a choice about expressivity  
>> vs computability guarantees.
>>
>> In typical OWL Full usage you get to use language features that you  
>> want, including ones that are not permitted in DL. You use these in  
>> the fashion that you want (whether neat or scruff). Then maybe an  
>> off-the-shelf reasoner and reasoner configuration gives you the  
>> trade-off you want between sufficient entailmenets vs speed - if  
>> not, you might need to customize your reasoning by selecting say,  
>> some rules out of a larger set of correct rules that cause a  
>> computational explosion.
>>
>> I fear that only having an informal, operational semantics for OWL  
>> Full would result in OWL Full being narrowed to only certain  
>> informal and less than precise work.
>>
>> Jeremy
>>
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>

"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 Tuesday, 12 February 2008 19:02:24 GMT

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