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Re: Primer ready for internal review

From: Ivan Herman <ivan@w3.org>
Date: Tue, 07 Apr 2009 15:41:31 +0200
Message-ID: <49DB580B.9060608@w3.org>
To: mak@aifb.uni-karlsruhe.de
CC: public-owl-wg@w3.org
Markus et al,

I have made a first review of the document, see details below.

All in all, I think there are some bugs in the examples that have to be
taken care of before publication. For some others that might require
more work an editorial note indicating that more work is to be done
should suffice by publication on the 15th.

Thanks for the huge work!



General comments

I have had my discussions with the editors on improving the formatting
of the turtle examples; this will happen, eventually. We also noted that
the encoding of rdf lists in turtle is currently bogus, and has to be


I missed a section on keys in the main section. I think keys are awfully
important in practice and should be listed and shown alongside the main
text (in section 4).


I think we agreed that the OWL 2 vs OWL 1 differences should move out of
this document, so I have not reviewed that section


On the section on profiles: for all three profiles what I miss is what
_cannot_ be done. Without these, it is fairly difficult to really
understand what is behind the shiny words that are used for
characterization:-) Maybe by listing those constructions in the generic
example that would _not_ fit into the given profile would give some
insight; possibly even more than the possibilities that can be done,
which is what is there now. Or listing both.


General comment on all examples. I use the example in  Section 3.1
because I just realized it while reading that one...

Technically, the RDF/XML syntax should say

<owl:Class rdf:about="#Woman">
   <rdfs:subClassOf rdf:resource="#Person/>

Similarly, the turtle should say

:Woman rdfs:subClassOf :Person

or, as it stands in the Appendix

f:Woman rdfs:subClass f:Person

The Appendix actually uses the proper syntax. I realize that the
examples might become a bit uglier, but I believe they should be
syntactically correct....

Also, in other examples, you have statements like

 <rdf:Description rdf:about="John">
   <hasWife rdf:resource="Mary"/>

that is, technically, correct for RDF/XML, but it might be better to use
the f:hasWife form for the predicate. Having said that, the
corresponding turtle example:

 John hasWife Mary .

is _not_ correct, it has to say either :hasWife or f:hasWife.


I believe that mainly the introductory part of section 8 needs a rewrite
(and possibly the rest of the paragraph, too), because it is not in line
with the intention of the 'naming' discussion that we had. DL is a
syntactic subset, does not automatically mean direct semantics; as we
put it into the overview, we have a common usage of Full equated to OWL
plus the RDF based semantics, but we should not emphasize that the way
it is done here.

I actually wonder whether we should have a long description here, and
whether we should not simply refer to what has been written in the
overview, and showing the effects of some of the DL syntactic restrictions.


Specific comments

Section 1.1, first paragraph

'This documented' -> 'This document'


1.2 Syntaxes

I think that, for consistency with other document, we should remove the
reference to CURIE-s. This is a primer and not a formal spec, so the
text is probably o.k. without it. It may be worth adding a sentence that
all syntaxes provide syntactic means to define such prefixes and references


Section 2, paragraph right before the editor note, 3rd sentence:

'Later' -> 'Latter'


Section 2, last paragraph, end of the 4th sentence:

'also the latter is' -> 'the latter is also true'


Section 3.4, 2nd paragraph after the first example

'Note that it is necessary to mind the order in which the individuals
are written down' ->
'Note that the order in which the individuals are written down is important'

Same paragraph, third sentence: 'Indeed ' -> 'Indeed, '

The right term in the FS for negative object property assertion is:
NegativeObjectPropertyAssertion and not NegativePropertyAssertion.


Section 3.8

The right term in the FS for negative data property assertion is:
NegativeDataPropertyAssertion and not NegativePropertyAssertion.


Section 3.8, just wondering about the RDF/XML encoding examples...

I know that the usual approach of encoding datatypes is to use the XML
entity facilities, eg, &xsd;integer. But for the reader it might be
worth (in the introduction) to make this clear, similarly to the
sentence on prefixes and references. Alternatively, we could byte the
bullet and write the full URI for datatypes. I have a slight preference
for the latter.


Section 4.1., after the first example block:

'this is, that all ' -> 'this is that all '

after the example on complements:

'But of course,' -> 'But, of course,'


Section 4.2, after the example on universal quant.

'occurs far more frequently;.' -> 'occurs far more frequently.'


Section 4.2, example on the usage of both the universal and existential
quant., in the RDF/XML example the </owl:intersectionOf> is missing in
the second block.


Section 4.2, before the last but one example block.

'class of individuals which are related to one particular individual' ->
'class of individuals that are related to one particular individual'


Section 4.3, first paragraph

'The following example states that John has at most four children that
which are themselves parents' -> 'The following example states that John
has at most four children who are themselves parents'


Section 5, first paragraph

'By now, our considerations were focused on classes and properties were
merely used as building blocks for class expressions.' -> 'Until now we
focussed on classes and properties that were merely used as building
blocks for class expressions'.

Section 5.1, 2nd example block

- the indentation of the ')' for the FS example is wrong
- there is a '7>' instead of '>' in the RDF/XML

Section 5.1, example on disjoing properties

Stricly speaking the RDF/XML and the turtle examples do not generate the
same triples; the RDF/XML encoding also generates the

hasChild rdf:type owl:ObjectProperty .

which is not part of the turtle encoding. Either this could be added to
the turtle encoding or one can simply say

<rdf:Description rdf:about="hasParent">...

not a big deal, but it may be better to keep these two strictly
identical triple-wise...


Section 5.1, text before functional properties

'As every person can have only one husband, '

is it true everywhere in the globe? :-) Just add a caveat...


Section 5.1, text after functional properties

'Mark that this statement does' -> 'Note that this statement does'

'It is also possible to indicate, that ' -> 'It is also possible to
indicate that '


Section 5.2., property chains

The RDF mapping of property chains have changed recently. The two
example syntaxes should be:

<rdf:Description rdf:about="#hasGrandparent">
	<owl:propertyChainAxiom rdf:parseType="Collection">
		<owl:ObjectProperty rdf:about="#hasParent"/>
		<owl:ObjectProperty rdf:about="#hasParent"/>

f:hasGrandparent owl:propertyChainAxiom (f:hasParent f:hasParent) .


Section 7.1 on the RDF/XML and turtle examples: as before there is a
discrepancy between the OWL/XML and the turtle examples, because the
former would generate an extra triple defining Person to be a Class,
whereas this does not happen in turtle.

Also, either use a datatype in both cases or don't. In fact, the
datatype is not really necessary here, a plain literal is just as fine.


Section 7.3. paragraph after the example block:

'However, the an IRI may denote different entity-types ' -> 'However, an
IRI may denote different entity-types '

I am also not sure that the term 'punning' is used in the rest of the
documents, and it certainly does not have any real sense in terms of OWL
Full. The full paragraph is, in fact, only OWL DL specific. It should be
moved and possibly rephrased to the OWL DL vs Full section.


Section 9

So you might choose to use a profile that doesn't fit as well with your
modeling problem in order to use the better Java tool. Before making a
major commitment we would suggest at least consulting with
public-owl-dev@w3.org which hosts such discussions, or consulting with
an expert.

This paragraph, though probably true, would really just scare away
people, think of the LC comment of Susie Stephens! I would rather not
have it here.


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, 7 April 2009 13:42:11 UTC

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