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RE: ebXML Registry UC (Was Re: Agenda: RDF Data Access 27 Jul 2004)

From: Jos De_Roo <jos.deroo@agfa.com>
Date: Tue, 3 Aug 2004 22:09:01 +0200
To: Jeff.Pollock@networkinference.com
Cc: "Farrukh Najmi" <Farrukh.Najmi@Sun.COM>, "Jim Hendler" <hendler@cs.umd.edu>, "RDF Data Access Working Group" <public-rdf-dawg@w3.org>, public-rdf-dawg-request@w3.org, "Rob Shearer" <Rob.Shearer@networkinference.com>
Message-ID: <OF388A821A.39AD26F4-ONC1256EE5.006D2581-C1256EE5.006EAA98@agfa.com>

Jeff, we should discuss this elsewhere, but when you write
* Reliability - if the answer to a query is implied by
    any of the model data, it will be found - guaranteed.
I'm VERY confused... I've been closely involved with
especially 3. Entailment Tests (29 Approved DL)
and I just can't find supporting evidence...

Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/

"Jeff Pollock" <Jeff.Pollock@networkinference.com>
Sent by: public-rdf-dawg-request@w3.org
03/08/2004 21:39

        To:     "Jim Hendler" <hendler@cs.umd.edu>, "Farrukh Najmi" 
<Farrukh.Najmi@Sun.COM>, "Rob Shearer" <Rob.Shearer@networkinference.com>
        cc:     "RDF Data Access Working Group" <public-rdf-dawg@w3.org>
        Subject:        RE: ebXML Registry UC (Was Re: Agenda: RDF Data Access 27 Jul  2004)


I'm getting tired of reminding RDF people about why DL's are such an
important part of the tech stack.  ;-)  Without it, there is no
standardized or reliable inference capability that can guarantee same
answers across different reasoner implementations. UDDI 3.0, OWL-S and
many Bio/Pharma ontologies among others have chosen the DL based
approach for good reasons. No one will argue that a DL view of things
requires a conceptual shift, or that there are indeed technical
limitations with what may be modeled. But in many cases the advantages
outweigh the disadvantages.

Regarding the RegRep, the SCM team has not yet debated the different
levels of OWL support.  I, for one, think that DL is a reasonable
alternative to seriously consider. Depending on the level of RegRep
specification, it may be a needed requirement.  For example, if the
RegRep simply exposes an OWL model as the interface to the repository -
leaving it to vendors to implement their own query support - then
restricting the interface to DL would enable an assured consistency in
"inference at query" results across vendor implementations. Otherwise,
different proprietary chaining algorithms could conceivably turn up
different results from different vendors - causing chaos in a
distributed DNS-like architecture.

I know you saw my prezo at the '04 W3C AC Rep mtg, but here's a reminder
of what I was saying regarding why DL's matter:

* Consistency - query results, across vendor implementations and
instances, should be consistent
* Performance - Although performance metrics depend on model constructs,
OWL-DL supports highly optimized inference algorithms
* Predictable - semantics are mathematically decidable within the model,
reasoning is finite
* Foundational - provides a baseline inside applications for layered
semantic models
* Reliability - if the answer to a query is implied by any of the model
data, it will be found - guaranteed.

Lest people be fearful of DL's, which could happen if your points are
taken out of context, I simply wanted to say that are indeed good
reasons why they exist.

Also, for the benefit of stating what should be obvious - Network
Inference embraces and supports ALL of the semantic web stack - RDF,
OWL-Lite, OWL-Full, and OWL-DL. Like you, we think that there are
appropriate times to leverage all aspects of the spec.

Time for me to get off the soapbox!

Best Regards,


-----Original Message-----
From: public-rdf-dawg-request@w3.org
[mailto:public-rdf-dawg-request@w3.org] On Behalf Of Jim Hendler
Sent: Tuesday, August 03, 2004 9:56 AM
To: Farrukh Najmi; Rob Shearer
Cc: RDF Data Access Working Group
Subject: Re: ebXML Registry UC (Was Re: Agenda: RDF Data Access 27 Jul

Farrukh, thanks for your response to Rob - I've gotten tired of
reminding him and others that the DL methodology is only one of the
ways OWL can be used (and in practice, it's not even the most common
- most OWL out there falls in Full, not DL) - it also has the problem
it is not yet scaleable to some of the largest Lite/DL ontologies out
there, and these are precisely the ones I want to access via query
instead of "document" (since the documents can get huge and take a
long hours to download, parse  and classify).  Tools that will admit
to the reality of the world out there and help people process it will
be quite welcome
p.s. Note, this is nothing against using DL when appropriate, as in
many of NI's business uses, but just to make it clear that DL is only
one of many ways OWL is being used, and it CANNOT be the defining
restriction for all use cases and applicability ... oops, I'm
starting to get passionate and use uppercase - I'll stop now...

At 10:26 -0400 8/3/04, Farrukh Najmi wrote:
>Rob Shearer wrote:
>>Greetings, Farrukh!
>>Apologies for not initiating contact myself.
>>Your use case came up at the face-to-face, and I was curious whether
>>there were alternative ways to achieve the results you were trying to
>>You suggest a method of "query refinement" to select the elements of
>>ontology in which you're interested: first do a general query, then
>>a few more qualifying predicates, then add a few more, each time
>>a look at the result set and figuring out what to add to prune out the
>>results in which you're not interested. (Please correct the most
>>offensive bits of this crude summary.)
>>In traditional description logics systems, the process of "concept
>>refinement" is most commonly implemented by traversing a concept
>>taxonomy using not just "subclass"-style edges, but rather
>>"direct-subclass" relationships. For example, a taxonomy of "Worker",
>>"White-Collar Worker", and "Accountant" would include both
>>Worker" and "Accountant" as subclasses of "Worker", however only
>>"White-Collar Worker" would be a direct subclass.
>>The common use pattern would be a user interested in "Worker", so the
>>user asks for the direct subs of worker and finds that they are "White
>>Collar", "Blue Collar", "Service", and "Military". He can then drill
>>down on whichever of these he wishes, each time getting a fairly small
>>and easily-consumed result set. This is usually much easier to manage
>>than trying to figure out how to refine hundreds, thousands, or
>>of results by hand somehow.
>>Is any approach along these lines applicable to your use case?
>I totally agree with sub-class refinement as the most common narrowing
>The use case envision the query to have zero or more parameters. Any
>of the parameters
>MAY be a Concept in a taxonomy (or a class in an Ontology).
>This is implied but not stated in the use case as I was trying to have
>description that was easy to follow and conveyed the core use case.
>If you would like to propose a modified version to the use case text
>send me a draft and
>we can try and reach closure on the issue before the next DAWG meeting

Professor James Hendler
Director, Semantic Web and Agent Technologies     301-405-2696
Maryland Information and Network Dynamics Lab.    301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742
Received on Tuesday, 3 August 2004 16:09:37 GMT

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