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[Fwd: comments on OWL Last Call drafts]

From: Dan Connolly <connolly@w3.org>
Date: 14 May 2003 11:03:39 -0500
To: www-webont-wg@w3.org
Message-Id: <1052928219.20121.536.camel@dirk.dm93.org>

I generally try to refine subject lines to be
more focussed, but I'm afraid that in this case,
he really is making comments on pretty much
all of OWL...

I think some of what he's asking for conflicts
with our charter, and the chair should prevent
that from taking WG time...

But I wonder about a dialog from the Overview/Requirements/Guide
perspective about the impact we expect OWL
to have on the problems Mr. Laskey expresses
interest in. Deb? Frank? Jeff? Chris? Any takers?

Some thinking-out-loud on specific points...

-----Forwarded Message-----

> From: Ken Laskey <KENNETH.J.LASKEY@saic.com>
> To: public-webont-comments@w3.org
> Subject: comments on OWL Last Call drafts
> Date: 10 May 2003 11:36:15 -0400
> 
> I have been thinking about the OWL Last Call drafts for some time and 
> I have been troubled by a general feel of unease.  While the use 
> cases provide a broad range of interesting and useful scenarios,

[Kudos Jeff and company...]

> my 
> general feeling is that OWL as presented will not be an effective 
> means to accomplish these ends.  I would be more comfortable if I 
> could point to specific shortcomings that I could suggest be 
> corrected (such as the n^2 problem with disjoint classes - why not 
> have a mutuallyDisjoint construct that is applicable to a list of 
> arguments?),

This isn't the main point of his comment, so we shouldn't
spend much energy on it, but we can show that the WG
considered that very question:

http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.21-drop-disjointUnionOf

with a resulting work-around in the guide:

  "A common requirement is to define a class as the union of a
  set of mutually disjoint subclasses. ..."

  -- 5.3. Disjoint Classes 
  http://www.w3.org/TR/owl-guide/

> but my issues go deeper than this.  In discussions with 
> others (including some outside SAIC), I have encountered a pervasive 
> feeling that OWL might be interesting but will not have significant 
> impact on real problems.  Any examples in the drafts that go beyond 
> the trivial are complicated and tedious, and it is unlikely that 
> anyone beyond a diehard would have the motivation to do any 
> significant ontology capture in this format.

I don't think we'd dispute that the language is complicated
and tedious, but we do have evidence that folks find the
functionality sufficiently valuable that they're willing
to build/buy/use tools to get their job done with it.

witness responses in the "Need to know about your implementations"
thread
  http://lists.w3.org/Archives/Public/www-webont-wg/2003May/thread.html#54


> What appears to be a significant shortcoming is the lack of explicit 
> support for real life problems that involve interacting ontologies. 
> While there is significant mention of ontology reuse and combining 
> independently generated ontologies, the drafts seem to miss the point 
> that independent ontologies have an overlap in coverage that in most 
> cases cannot be captured as a one-to-one equivalence but rather show 
> an incomplete and possibly inconsistent interpretation of a domain.

This is the bit that seems to be asking for something outside
our charter... for our language to specify anything other
than "yes, there's an inconsistency there" in the case
of an inconsistency would seem to go against our charter:

[[The products of this working group must be supported by a formal semantics
allowing language designers, tool builders, and other "experts" to be
able to precisely understand the meaning and "legal" inferences for
expressions in the language.]]
  -- http://www.w3.org/2001/sw/WebOnt/charter

but perhaps some stuff from guide/overview would be responsive
to what he's after...

> This is the information that gives value to ontology combination and 
> reuse. OWL has no means to capture this.  For example, if I have one 
> ontology where my name is captured as "Ken Laskey" and I have a 
> second ontology where nameFirst captures "Kenneth" and nameLast 
> captures "Laskey", how does OWL represent this correspondence at the 
> class level?  Note, even at the individual level, sameIndividualAs 
> may not be sufficient because a Google search identifies more than 
> one Ken Laskey, and it is not feasible to annotate each individual.

I'm not clear on what he's after. Sufficient for what?

> Moreover, search is evidential and inductive in nature. I need not 
> only to be able to do searches, but also to represent the partial 
> correspondences I find in the results.  How does OWL support the need 
> to show an accumulation of evidence towards a conclusion rather than 
> trivial cases where the answer is close-ended?

I don't think it does. (But maybe Deb/Frank/Guus/Chris or
somebody would take a different view?)

Meanwhile, we weren't chartered to do that.

It would have been nice if he'd reviewed the charter
and raised this issue then. And this point will be in order when
the Advisory Committee is asked to endorse our Proposed Recommendation.

But it's not in order at last call, i.e. technical review
of what we were chartered to produce.

>  In a real problem, I 
> need to be able to accumulate evidence about whether a new mutation 
> of SARS is appearing or whether I have a local increase in lethality 
> of the standard virus.  The ontology and the individual information I 
> need is much more fragmented than that which I would use to choose a 
> wine.
> 
> There are other concerns I have about OWL.  We are creating a means 
> of capturing information for use by other processing engines but I do 
> not see that we have a clear understanding of what these engines are 
> and what content and form of information these will need for their 
> tasks.  For example, the multimedia use case refers to a knowledge 
> fragment "typically made of mahogany".  How would a processing engine 
> draw this conclusion, store this conclusion, or use it in further 
> processing or search?  I know that there are many examples of how I 
> can specially craft an ontology to conceptually support such tasks, 
> but without a range of examples on how engines would actually do this 
> work, we do not know what information needs to be captured at the 
> meta level represented by OWL or how it should be efficiently 
> represented.

I personally am satisfied that experience with a "range of examples
on how engines would actually do this work" is represented in 
this working group. I'm not sure how to communicate it to
Mr. Laskey, other than to say "gee, if you had joined the WG,
you would have seen lots of exactly that."

Hmm...


> Now in response to many of my concerns, one could say we have to 
> start somewhere and OWL is as good as (if not better than) most 
> alternatives.  However, in work we have done at SAIC, we have seen 
> that when an ontology is created by one group of people (however 
> knowledgeable) for use by a wider community, the ontology reflects 
> the task priorities of the "first one in" and results in frustration 
> to those outside the process because it constrains use from a 
> different perspective.  Rather than facilitating discussion, the 
> initial view often stifles growth.  All too frequently, the result is 
> that the ontology is used only by its initial adherents.  One could 
> argue that this is what has happened with RDF.  A Working Group (even 
> one that endeavors to be inclusive) by nature codifies the context in 
> which it will do its work.  Given we all acknowledge that many 
> different ontologies represent various views of a domain, what 
> attributes of OWL overcome shortcomings of a single ontology created 
> by a single group and make it the single sufficient basis for a 
> general-use standard across the Web?

Again, this is not in order as a technical review comment, and
the chair should prevent it from costing the WG much time on
charter grounds.

Again, this would have been in order at charter-review time,
and will be in order at proposed recommendation time
(and we're glad that he shared his comment with us at
this point rather than later...)

But the WG's answer is sort of self-evident: this group
is doing its best to deliver on its charter.

In the end, what we're doing is biased by who shows up.
Yes, of course. And perhaps what we're doing is premature
standardization. But there's a process for review
of charters, and a process for endorsement of the
result. But right now, we're in the technical review
phase.


> Finally, in several places in the drafts, it is noted that "tool 
> support" will be required, such as for maintaining consistency for 
> merged ontologies.  However, I am concerned that there will be no 
> impetus to create tools unless OWL ontologies can be shown to be 
> useful without the tools and that tools will provide needed leverage 
> for people who find value in the manipulations the tools do.

Answer: stay tuned for our request for proposed recommendation.

>  Large 
> developers will not create tools just because the tools can do neat 
> things unless there is some rationale for a larger market.  Do we 
> have significant information that vendors will embrace OWL, either to 
> create tools or, more importantly, for use in their internal 
> infrastructure?
> 
> With these Last Call drafts, we are heading towards standardizing 
> something which does not clearly show the ability to enable solutions 
> on the scale of the Web.  The level of complication and the lack of 
> general robustness of artifacts built on OWL make it unlikely it will 
> be used for more than focused problems on a limited scale.  While 
> this may be useful for further research, moving forward to give the 
> imprimatur of a standard to something which is unlikely to have wide 
> and significant impact would only diminish the significance of W3C 
> Recommendations.  For this reason, I strongly encourage that the use, 
> purpose, and syntax of a web ontology language be rigorously 
> reconsidered.

Hmm... the charter was carefully considered.
The requirements were carefully considered.
The design was pretty carefully reviewed.
I wonder what makes Mr. Laskey think that doing it all
again would produce something significantly better or
different.

It seems to me that the only sane approaches are
  (a) stop! wait 5 years for the market to mature
	before standardizing an ontology language
  (b) go! get this thing out the door and see
  if it catalyzes the marketplace.

Yes, approach (b) carries a risk of "frustration 
to those outside the process because it constrains use from a 
different perspective". But we're here because
we believe the expected benefits outweigh the
expected costs.


> Ken Laskey

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 14 May 2003 12:05:34 GMT

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