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

From: Jim Hendler <hendler@cs.umd.edu>
Date: Fri, 12 Jan 2007 09:37:03 -0500
Message-Id: <p06230954c1cd47b78b01@[192.168.0.102]>
To: Bijan Parsia <bparsia@cs.man.ac.uk>
Cc: public-owl-dev@w3.org
As I promised - I might have some more comments - here are some:

I agree with many of Bijan's motivations (seeAlso his blog) but I 
have some concerns as to whether this fully considers some issues 
about the usability/marketability of OWL:

I focus on the section on scope viz the deliverables:

 From proposed charter (version in [1])
SCOPE
Extensions to the logic underlying OWL, adding new constructs that 
extend the expressivity of OWL (e.g., qualified cardinality 
restrictions).
Extensions to the datatype support provided by OWL, e.g., with XML 
Schema Datatypes and datatype facets.
Additional syntactic sugar, i.e., constructors that do not extend the 
expressive power of OWL, but that make some common modelling 
paradigms easier to express (e.g., disjoint unions).
Refinement of the OWL specification, e.g., a rationalization and 
tightening of the specification of the abstract syntax of OWL so as 
to better support APIs, and to allow for a deterministic and 
round-tripable mapping from the abstract syntax to RDF graphs.
Additional concrete sytnaxes for OWL ontologies. Notably, a new XML 
format designed for easy parsing and maximal compatibility with 
current XML practices.
Rationalization of the species of OWL. For example, identifying 
useful sub-languages that are (more) tractable and/or efficiently 
implementable, e.g., with standard relational and deductive database 
technology.
The working group should determine whether continuing the "species" 
framework for end users is the best way to serve the OWL community, 
or whether the identification of interesting fragments by the working 
group is "merely" informative.


(note: I admit that I have some worries that the order here reflects 
the group's priorities, but that's neither here nor there)

Anyway, my comments on this are that I think these are good goals, 
but when we look at the deliverables I don't see some things I think 
are needed

  1 -  There are a set of existing recommendation docs, esp. the model 
theory, the guide, the reference manual and the overview which are 
important to OWL.'s use.   The new charter says the group will:

The working group will work to ensure a smooth transition from OWL to 
OWL 1.1 by providing suitable outreach documents (whether new or as 
updates to existing documents), and by striving to maximize backwards 
compatibility, especially of ontologies.

I'd like to see a specific commitment to extending the 4 documents I 
mention above - doesn't mean new ones couldn't be written, but a 
group updating a spec should update the mandatory documents

2 - I am most worried, personally, about the "example, identifying 
useful sub-languages that are (more) tractable and/or efficiently 
implementable, e.g., with standard relational and deductive database 
technology" statement." (from [1])
  One mistake we made in the original OWL group was we did not spend 
enough time thinking about "usability" instead of theoretical 
aspects.    While I have no problem with the tractible subsets 
document, it very much does NOT answer the mail on this.   For 
example, syntactic considerations, ease of use considerations, and 
usability concerns are not included in that document - it is too much 
a theoretical aspect.  Oracle, for example, announced at ISWC the 
subset of OWL they intended to support, and it was not a maximal 
tractible subset - it was a smaller subset that they chose for issues 
including how straightforward it was to explain to their users.   I 
think it important to have a named subset of OWL that falls in this 
area - if the group is not willing to take this on, then the 
"rationalization" goal should not be included.

3 - Whil I like the idea of refinement of OWL specification, I would 
have trouble supporting a recommended normative syntax that is a 
"Deterministic and round-trippable" mapping from the syntax to RDF 
graphs - as this means arbitrary RDF graphs expressing OWL relations 
would not necessarily be able to "play" - but many different tools 
may use different encodings of the same information, and the 
information content, not its syntactic realization is the imprtant 
thing.
  I suspect this is just a wording thing - I think the scope of that 
goal should be a refinement of "A" OWL specification, not "THE" Owl 
specification - in particular, the abstract syntax should/must remain 
one of the ways OWL can be expressed, but RDF/XML needs to remain the 
normative data interchange format, or we can lose interoperability 
with the large and growing installed base of RDF tools and 
applications

4 - the scope seems awfully ambitious for a 1 year group, esp. when 
you consider the above.  I would recommend deciding whether to take 
all these things on and allowing more time, or cutting out some of 
these  (do XML spec or Owl species or refinement of spec - not all of 
them)


Finally - a quick note - please notice that compared to my earlier 
reservations about this WG, I feel this charter is a major 
improvement and these are all constructive criticisms based on (too 
much) experience with WGs, not meant to be "show stoppers" - but 
remember that for this WG to work, there must be players from outside 
academe, and for these more applied players, the sturcturing of the 
WG qua WG is as (and sometimes more) important than the list of the 
deliverables.   Getting the charter right is really important.

   -Jim H.



[1] http://lists.w3.org/Archives/Public/public-owl-dev/2007JanMar/0010



-- 
Prof James Hendler				hendler@cs.rpi.edu
Tetherless World Constellation Chair		http://www.cs.umd.edu/~hendler
Computer Science Dept			301-405-2696 (work)
Rensselaer Polytechnic Inst			301-405-6707 (Fax)
Troy, NY 12180
Received on Friday, 12 January 2007 14:37:51 GMT

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