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Action-322 Review of New features and rationale.

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Wed, 1 Apr 2009 12:50:37 -0400
Message-ID: <29af5e2d0904010950t5361502i9e5f01f6e0bf261c@mail.gmail.com>
To: W3C OWL Working Group <public-owl-wg@w3.org>
Review of New Features and Rationale.

On the positive side, I'd like to pass on a compliment given at a talk
I recently gave on OWL, saying that the NF&R was quite helpful.

In reviewing the document, the overriding concern I have in reading it is the
length. I would like to see it compacted. In my review I give some
examples. Detailed review is until section and is adequate to
the general issues and potential solutions. I will continue a detailed review
and send further comments.

 On review I don't see the need for the boxed syntax
 description. The examples serve to demonstrate enough of the syntax,
 and typographic emphasis could give an extra indication of which part
 of the example is demonstrating the feature.

 In the examples, the subject heading, e.g.  the word "HCLS" below
 "example", don't seem necessary and unnecessarily emphasize the noted
 bias towards examples from this area. Note: I prefere the expanded "Health Care
 and Life Sciences" instead of HCLS, in positions such as this, should
 these be retained.

 RDF examples need a leading ":" at least, as they need to be
 namespace qualified. The first example "BrainHemisphere" would be

 There is the need for a careful proofread for grammar. I have given
 examples where I have seen them.

 While I support the idea of having RDF syntax examples as well, I
 would like them to be implemented in the same way as in the other
 documents, if kept.

 Mathematic expressions are used to explain some features, but not
 others. I suggest we don't use them anywhere.

Section 2.1
 In the boxed examples, link UC#2. This also removes the need to list
 them as a separate line after the box.

Wording (appears for each of the two cases)
 "Implementations, however, may prefer to take special notices of
  DisjointClasses for more efficient processing"
 "Implementations, however, may prefer to serialize using
 DisjointClasses so as to minimize file size and parsing time."

"2.1.1 F1: DisjointUnion" use of the addition "F1" for cross
referencing doesn't seem necessary. Why not just cite the sections

Section 2.1.2

I would remove all or most of this note. If we keep anything, just
"The FMA exhibits a huge number of such classes [FMA C in

"Note: The FMA exhibits a huge number of such classes [FMA C in
Appendix]: 3736 classes of template Left X vs Right X (e.g. Left lung
vs Right lung) 13989 classes of template X left Y vs X right Y
(e.g. Skin of right breast vs Skin of left breast) 25 classes with
template Male X vs Female X (e.g. Male breast vs Female breast) 75
classes X male Y vs X female Y (e.g. Right side of male chest vs Right
side of female chest)"

If kept, it would be outside the example box.

The two examples are virtually the same. Drop one. I like the comment
on the second example better: "Nothing can be both a Leftlung and a RightLung"

Section 2.1.3

"While OWL 1 provides means to assert values of a property for an
individual, asserting that a property has not some values is
impossible. This requires the ability to assert facts about an
individual stating property values that it does not have"

If it were impossible in OWL 1 it wouldn't be syntactic sugar. In fact
it is possible but the alternative expression was deemed to be
cumbersome and raise the overall difficulty of reasoning because of
the use of nominals. It's probably worth writing one version of the
OWL 1 way.

You also say: "It's possible to take an ontology that is OWL 1 except
for NegativePropertyAssertion and preprocess it into an equivalent OWL
1 ontology without it."

I think it would be better to have the Theory and Implementation once
for the whole section to reduce size, since it applies to all the
cases of syntactic sugar.


Section 2.2.1

Drop:  "For example, it might be appropriate to state that the
skos:broader relationship is only locally reflexive or, alternatively,
locally irreflexive w.r.t. skos:Concept (see also F6). "

It's said in F6 anyways and confusing without the larger explanation.

"Note: Global reflexivity may be used for local reflexivity in
profiles which do not have local reflexivity (e.g., OWL 2 QL)."

I don't understand this - global doesn't mean the same thing. Drop.

Theory and implementation.

"The description logic underlying OWL-DL is SHOIN. OWL 2 is based on a
more expressive description logic: SROIQ [SROIQ]. SROIQ extension of
SHOIN was designed to provide all possible useful additions to OWL-DL
that were requested by users, while not affecting its decidability and

This is something that is globally relevant. Include in the
introduction, but not here, I think.

The next seems unnecessary, or part of the introduction at best.

"SROIQ logic extends SHOIN with reflexive, asymmetric, and irreflexive
roles, disjoint roles, a universal role, and constructs ∃ R.Self. It
also allows qualified number restrictions and negated role assertions
in Aboxes. Additionaly, SROIQ offers complex role inclusion axioms of
the form R ◦ S < R or S ◦ R < R to express propagation of one property
along another one, which have proven to be very useful in particular
for biomedical ontologies (see F8: Property chain inclusion)."

Maybe keep this. Interested in feedback from others. But I'd lean towards
dropping it.
"Local reflexivity is already supported by existing tools, e.g.,
FACT++. According to developers, local reflexivity was relatively easy
to implement [TOOLS] – for any individual x that must have a
relationship along a reflexive property, an appropriately labelled
edge <x, x> has been added to the model."


A good example of where dropping the syntax boxes and the domain
headers would make this a more easily readable section.

Drop "The following examples are some examples of Object Property
Cardinality Restrictions from Use Cases among many in HCLS."

"Class of objects having at least 5 direct part" s/part/parts/

"Class of objects having atmost 5 Door" ->
"Class of objects having at most 5 doors"

"Class of objects having exactly 2 RearDoor"->
"Class of objects having exactly 2 rear doors"



"As already said above, qualified cardinality restrictions are present
in the SROIQ description logic underlying OWL 2 since they were
required in various applications e.g.; [Medical Req] [Little Web] and
did not pose theoretical or practical problems to be added [SHOIQ]. It
has been known from a long time that resulting logic is decidable and
QCR was already supported by DAML+OIL, the predecessor of OWL 1. QCRs
do not pose an implementation problem either. It has been successfully
implemented both in earlier editor, e.g.; OilED, and reasoner, e.g.,
FACT++, that already processed ontology with QCRs, before OWL 1
recommendation. Current versions of tools under development for OWL 2,
e.g.; Protégé 4, FACT++, PELLET, RACER, KAON2 also deals with QCRs

"It has been known for some time that OWL extended by qualified
cardinality restrictions is decidable and  they were already supported by
DAML+OIL, the predecessor of OWL 1[cite]."


I suggest we remove this, as we don't support the antisymmetric
properties needed for mereology, and in any case you can't use these
property types with the transitive (i.e. composite) property part_of.

"For example, in mereology, the partOf relation is defined to be
transitive (if x is a part of y and y is a part of z, then x is a part
of z), reflexive (every object is a part of itself), and antisymmetric
(if an object has a part which in turn has part itself, then they are
the same). Many applications, particularly those where it is necessary
to describe complex structures, such as life science applications or
more generally for systems engineering, require extensive use of
part-whole relations, axiomatized according to these principles"

Also drop "Other relations encountered in ontology modeling require
similar axiomatizations as well, possibly with different sets of
characteristics (see, e.g., [OBO] [RO])."

"Another interesting example" -> "An interesting example"

"SKOS specification" -> "The SKOS specification"

Rewriting a bit: "The SKOS specification [SKOS] makes no committment
to the reflexivity or irreflexivity of the skos:broader
relationship. The specification mentions that skos:broader should
be considered reflexive "for a direct translation of an inferred OWL
subclass hierarchy", but that irreflexive would be "more appropriate for
most thesauri or classification schemes". With the addition of reflexivity and
irreflexivity, OWL 2 allows one to express either of these choices.

Self restrictions are even more fine grained, by allowing one to state
that skos:broader should only be locally reflexive or irreflexive
w.r.t. skos:Concept."

Move to example box:

One can make skos:broader locally irreflexive w.r.t. skos:Concept via an axiom
SubClassOf(skos:Concept ComplementOf(ObjectHasSelf(skos:broader)))
i.e. if x is a skos:Concept, then NOT( x skos:broader x ).


I don't think that we need the mathematical expression. We don't do
that uniformly.

Comment says: "Everybody has the same blood group as himself" Should
say "Every thing has the same blood group as itself". If you want to
make it about people then it needs to be locally reflexive.

I believe the example violates the global constraints.
AsymmetricObjectProperty( proper_part_of )

As propert_part_of is transitive.

Theory and Implementation
Include only "see F4 Theory and Implementation above Impementation was
similar to the approach taken to support local reflexivity."
Received on Wednesday, 1 April 2009 16:51:28 UTC

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