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Closing action-306: Comments on the QRG

From: Ivan Herman <ivan@w3.org>
Date: Tue, 17 Mar 2009 16:57:50 +0100
Message-ID: <49BFC87E.3080607@w3.org>
To: W3C OWL Working Group <public-owl-wg@w3.org>
For the records, these were my comments on the QRG document. In fact,
these comments went to Jie before I took the action last week, and the
current wiki page reflects most of the proposed changes already. But as
there was a public action on me, it is better to have that on record, too.

Ivan

---------------


- The explanation for the [...] syntax for lists is in 1.6, although it
is used right at the begining already. I wonder whether it is not better
to move that section up where the notations are described. After all, as
far as this document goes, this is a notation. (I am not even sure it is
worth spelling it out in terms of triples, just make a reference to the
appropriate RDF Semantics entry.)

- The term 'self' is used in the fourth entry of table 1.1.2. Wouldn't
'local reflexivity' be a better term?

- 'Restrictions Using Object Properties owl:Restriction' in 1.1.2 and
1.1.3 appears right before the tables. I am not sure why you have
'owl:Restriction' listed there there. I do not think it is necessary.
Actually, the rest of the line is just the section heading which does
not seem to add any new information. I would propose to leave only the
second line there ("Every owl:Restriction is an owl:Class.")

This is something that is repeated all along. There is a section
heading, and then the same text as the section heading is repeated in
bold referring to some owl vocabulary element. I do not see the value of
these; just shorten things by removing them (I realize the PDF card may
need that, but then this should be visible on the PDF only...)

- I wonder about the treatment of n-ary datatypes in 1.1.3. We have them
_syntactically_ as 'hooks' in the spec, but they are not part of the
core spec. I wonder whether the corresponding two lines (n-ary universal
and n-ary existential) should not be clearly separated from the rest
with a clear statement warning the user that these are _not_ part of the
core OWL 2 spec. Editorially, this also means (I guess) that the D^n
reference from the intro paragraph in section 1 should be moved out to a
separate place

- 1.1.4 just for the sake of consistency: 1.5 includes an abbreviated
format for SameIndividual when there are more than 2; I think the same
format should be used for, eg, EquivalentClasses, or for similar
constructions elsewhere

- in 1.3.1. I would repeat the top/bottom property term in the third
coloumn. The reader might be misled by the table to think that those
terms are not available in RDF. It is redundant, I know, but, well...

- 1.3.1. In my understanding the property chain (ie,
ObjectPropertyChain) appears in a subproperty position only, ie, as it
appear in the second row of 1.3.2. I guess this should be checked with
Boris and Michael. If I am right (which is not sure...) it should
probably be removed from 1.3.1. In any case, the owl term used is wrong,
it should be owl: propertyChainAxiom.

- 1.3.2. I wonder about the fourth coloumn of the table. I am not 100%
sure we should have those there or, if we do, whether we should have it
for all entries. Again, I am not sure, but there is a level of
inconsistency there:-(

By the way, strictly speaking in the RDF semantics, some of the
statements are not 100% correct. Functional property means that

i0 P i1. i0 P i2 => i1 owl:sameAs i2

I know, I am nit picking, but, well... (the same is repeated all along
that coloumn)

- I am not 100% sure the first table in annotation (1.9) is correct
although, I must admit, I am not sure how to put this whole annotation
business in concise form:-(

If I have Annotation(P v), and this appear within an axiom, ie something
like

SubclassOf( Annotation(P v) A B )

this gets translated into the triples

A rdfs:subClassOf B
_:x rdf:type owl:Axiom
_:x owl:subject A
_:x owl:predicate rdfs:subClassOf
_:x owl:object B
_:x P v

ie, the first triple in the table (y P v) does not seem to be correct...

- 1.9.2, again I am not 100% sure about the annotation assertion. If I use

AnnotationAssertion(p SomeURI v)

this gets translated, simply, into

SomeURI p v

ie, no extra reification there...

- Section 2: just a heads up: Boris is rewriting this part as we speak,
so this may have to be updated at some point, too.

- Section 4

I wonder whether this should not be moved to the top of the page. These
are the namespaces we use, better specify them upfront...

Minor nit:

- This is a matter of taste, of course. Personally, I find the gray
background shading a little bit disturbing. I wonder what other
typographic trick we should use to denote OWL 2 specific features, but
something less disturbing would be nice. (Maybe some lighter colour, for
example?) I also wonder whether we could find a trick (eg, by chaning
the css values via a javascript?) so that I could choose _not_ to
highlight the differences. It is of course great to have those clearly
denoted for those who make a transition from OWL 1 but, after a while,
these differences become without interest, and I might prefer not to
have them highlighted at all. The same holds for the '?' links that
refer to the NF&R; once people are hooked on OWL 2, those issues become
moot, and the really important reference will be the primer (in my
view...) and not that one...

-- 

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Tuesday, 17 March 2009 15:57:44 UTC

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