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Re: Responses to "Draft of charter for NextWebOnt (Proposed) Working Group"

From: Phillip Lord <phillip.lord@newcastle.ac.uk>
Date: Mon, 15 Jan 2007 11:44:11 +0000
To: public-owl-dev@w3.org
Message-ID: <ufyacqzuc.fsf@newcastle.ac.uk>

>>>>> "JH" == Jim Hendler <hendler@cs.umd.edu> writes:

  JH> but let me be clear - I think there are two approaches that
  JH> would be valid for the Working Group - either take usability and
  JH> the real world into account, or leave the task of defining other
  JH> OWL subsets to people who do.  What is a mistake is for the
  JH> group to take it on and do it on purely theoretical grounds -
  JH> all we'll end up with another travesty like OWL Lite


Accept my apologies if I have attributed this to the wrong person. I'm
finding it very hard to work out who has said what, and what is new in
Jim's emails. 

I would say that the second option -- "leave the task [...] to people
who do"-- is not really an option. If people are going to define OWL
subsets, then the working group should at least have a mechanism for
specifying and describing these subsets in a standard way, even if it
chooses to define no subsets. If you want a (vaguely) equivalent
situation, I would suggest the Gene Ontology "slims"; this is a
mechanism for defining subsets of a given ontology, rather than
ontology formalism. These happened because everyone was defining their
own subsets of GO.


  JH> if the WG wants my opinion, they should remove that topic from
  JH> the scope - but if that's not viaable, then expect that there
  JH> will be those of us who insist that the WG pay attention to
  JH> things that are not "measurable" and require us trusting
  JH> people's instincts and experiences, which makes many formalists
  JH> very nervous.


Usability is just as measurable as tractability, I would say. As far
as I understand it, the complexity of solving a DL is determined by
it's expressivity. But as a user of DLs I don't actually care about
the complexity, rather how fast the reasoner runs which is just not
the same thing (or if they work at all, which was quite a while for
OWL-DL). 

There are a number of ways in which usability could be tested. We
could gather up a set of curated ontologies and find out which
constructs are used most often; naive users could be surveyed with
descriptions of the constructs and questions about the implications,
to see which attract most frequent confusion. 

Of course, these measures will not be perfect. They will fail to give
an exact answer about what is good and what is not good expressivity
for the users; but, then, provable complexity of the different
expressivities doesn't give you an exact answer as to what is going to
run fast in practise which is what most people actually care about.

As for making formalists nervous, hey, well, somethings you just have
to live with. They can take beta-blockers or something. 

Phil
Received on Monday, 15 January 2007 11:44:29 GMT

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