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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.



- 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

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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