a few comments about the OWL 2 drafts

I have a few (mostly minor/editorial) comments on the December 2 drafts:

An overall editorial comment/request:
- Could you create HTML anchors for all definitions in the documents?  I
would like to be able to link directly to definitions of, e.g., datatype
maps and vocabularies.

=== Syntax ====

- the definition of datatypes in section 4 lacks the lexical-to-value
and facet-to-value mappings [these are clearly part of the datatype]
- for the datatypes you rely on XML Schema 1.1 datatypes, and you seem
to have included most of them that make sense.  But you have not
included precisionDecimal.  Is there a rationale for that?
- the difference in your definition of the value spaces of hexBinary and
base64Binary (i.e., non-disjoint) and the definition of XML schema
(i.e., disjoint) should be pointed out in the document, as you did for
the numeric types
- I strongly suggest you use the PNG format for the images in the
document, rather than GIF.  I suspect this is even W3C policy.


=== Direct Semantics ===

- Some definitions are difficult to read, because they rely on terms
defined in another document.  When referring to a term defined in
another document (e.g., the syntax specification), could you include a
direct link and a reference (e.g., [OWL-Syntax])?  I think this would
help the reader.
- why a new definition for datatype maps?  Why not use the same one as
in RDF and OWL 1?  The definition of interpretation would become a
little bit more complex, but I don't really see that as a problem.
- in the definition of interpretation, using "Int" for the object domain
is rather unfortunate, because it could be confused with the set of
integers.  I would suggest "Obj" or "I".
- first sentence of section 2.3: the definition of satisfaction should
explicitly refer to the tables that contain the conditions of
satisfaction.  "Appropriate conditions" is not sufficient.
- I could not find the definition of the term "axiom closure".  It is
used in several places.
- section 2.3: we have separate subsections for the different tables?
Each subsection only contains one sentence in the table, and the
sentences are very much alike.  One could simply write one sentence and
refer to all tables, and get rid of the subsection headings.
- in section 2.3.6, the comment in the parentheses about renaming
anonymous individuals should be made part of the definition, i.e.,
should not appear in parentheses.
- in section 2.5, "variable" is not defined.
- paragraph before section 4, first sentence: "is is" => "is"
- it is probably a good idea to refer to the second edition of
description logic


=== Profiles ===

- in OWL 2 RL I do not understand why the following features are not
included -- they are easily implemented the rules:
* ReflexiveObjectProperty
* owl:Thing
* negative class and property assertions
- in section 6, I could not find the "productions defining the general
concepts of the language". could you include a direct link?
- section 6.1 and 6.3: "subObjectPropertyExpressions" =>
"subObjectPropertyExpression"


=== RDF-Based Semantics ===

- if there are differences between the datatypes and facets in tables
2.2 and 2.3, on the one hand, and the datatypes and facets in that
syntax specification, these should be mentioned.  If there are no
differences, this fact should be mentioned as well.
- in my opinion, this document should use exactly the same definition of
datatype map as the direct semantics specification.
- above definition 4.2: "a OWL" => "an OWL"
- I do not understand the purpose of section 6.  There are no notions of
consistency or entailment that could be implemented, so I don't see how
anyone could exploit theorem 6.1.

-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/
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No one who cannot rejoice in the discovery of
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scholar.
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