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Re: update to the feature synopsis document

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 15 Jul 2002 10:13:27 -0400
To: dlm@ksl.stanford.edu
Cc: www-webont-wg@w3.org
Message-Id: <20020715101327I.pfps@research.bell-labs.com>

		Commentary on
		Feature Synopsis for OWL Lite and OWL
		Version of 8 July 2002


- The abstract contains the same sort of inflated claims that pepper the
  RDF documents.  It should be changed so as to not implicitly claim that
  OWL can handle arbitrary logical content.  Similar problems occur in the
  first paragraph of the introduction, which repeats the first 2 1/2
  sentence of the abstract verbatim, a definition no-no. The abstract is
  too long in any case.

- The introduction is rather repetitive.  In particular, it introduces OWL
  Lite twice.  Among other changes, the last paragraph could be removed.

- The numerous design goals for OWL Lite are contradictory, and do not
  correspond with the existing language.  It would probably be better to
  drop the extension design goal.

- The listings of feature constructors need more introduction, i.e., more
  is needed at the beginning of Section 2.1.  (What is a ``feature
  constructor'' by the way?)

- The feature constructors do not correspond to those in the reference
  description document, nor do they correspond to those in the abstract
  syntax document.

- The document assumes a rather high level of understanding of its readers,
  for example 
  - in its use of ``description'' and related terms near the beginning of
    Section 3 
  - in its use of ``model'' near the beginning of Section 3.1
  - in its use of ``sentence'', e.g., in Section 3.6
  This is fine in a reference or formal document, but not very good in
  a synopsis document.  

- The document talks about ``valid'' OWL statements.  What does this mean?

- The Mammal example is very confusing.  What is the relationship between
  ``Mammal'' and ``THING''?  What is ``the description THING''?

- What is the relationship between the tokens in Section 2 and the headings
  in Section 3?  What is the relationship between these and anything in OWL
  Lite or OWL?  This points out a very serious problem with the document -
  its purpose is not given.  Is the document trying to provide a high level
  description of the features in OWL Lite and OWL?  If so, what are the
  comments about abstract syntax?  Further, the high-level descriptions do
  not correspond to either the abstract syntax document or do the reference
  description document.  (See, for example, the Class and Property entries
  in Section 3.1.)  Is the document trying to describe the abstract syntax
  or the triple syntax?  If so, where are these relationships made clear?
  This confusion is made clear in Section 5, where the first sentence talks
  about a feature synopsis (not syntax) but the second talks about
  constructors (syntax).

  I recommend that this document use precise names (like functional) for
  all these things, and try hard not to use the DAML+OIL or OWL names.  The
  document would be limited to providing a very high level description of
  the functionality provided in OWL Lite and OWL, and would not mention any
  syntax at all.  As part of this, Section 2 would be removed.  Discussion
  of functionality would not be organized around syntax (e.g.,
  minCardinality, maxCardinality, and cardinality in Section 3.4) but would
  instead be organized around functionality (e.g., Section 3.4 would just
  talk about cardinality, with min- and max- being mentioned inline).  Two
  examples of how this could work are Section 3.5 (without the last
  sentence and the gratuitous one-element list) and the paragraph on oneOf
  (without the heading).

- The introductory sentence in Section 3.3 does not correspond to the first
  element of the list.  Similarly, the last two entries on this list have a
  very different behaviour from the previous four and deserve to have a
  separate introductory bit.

- The document is rather confused about classes and descriptions.  For
  example, classes are used in Section 3 in contrast to descriptions, but
  in Section 4, classes appear to include descriptions.  In Section 4, the
  phrase ``complex class descriptions'' is used as well. 

Minor problems:

- The title should probably be changed to be more in line with the reference

- The formal spec document does not contain a formal semantics for OWL.

- The constructors should probably have owl: in front of them, where
  appropriate, otherwise, rdf: or rdfs:.

- functional is used instead of unique

- The comment on hasValue is misleading.  There is no hasValue at all in
  OWL Lite.

- The sentence about instance probably does not belong in the paragraph
  about Property.

- This will be the first version of the document, and thus there should not
  be a history.

Editorial problems:

- ``a languages''

- The paragraph starting ``This smaller language'' should instead start
  ``OWL Lite''.

- The first paragraph of Section 2 does not read well.  The italicized
  terms term should probably be italicized.
- The individual feature is not italicized.  Is this correct?

- Section 3 exists, so it discusses something.  Stating that it ``will
  discuss'' something gives the impression that it does not now do so.
  Similarly, ``proposed'' gives a very tentative impression.

- The first sentence of Section 3 should reference OWL Lite, as in the
  ``language features of OWL Lite''.

Peter F. Patel-Schneider
Bell Labs Research
Received on Monday, 15 July 2002 10:13:37 UTC

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