- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Mon, 23 Sep 2002 06:54:08 -0400 (EDT)
- To: phayes@ai.uwf.edu
- Cc: www-webont-wg@w3.org
On a quick read through of part of the new document I found the following
issues. I'm assuming that rdfs:subClassOf, rdfs:subPropertyOf,
rdfs:domain, and rdfs:range are strengthened to iff. Without this
strengthening, many more of the claims in the document are incorrect.
- owl:UniqueProperty is not in OWL.
- Making IOC and IOP sets of sets doesn't seem to have any impact. The
fact that ICEXT(IS(owl:Class)) is a set of sets doesn't make ICEXT(IS(foo))
have any relationship to IS(foo), for foo in ICEXT(IS(owl:Class)).
- owl:DisjointWith is incorrect. There is no reason to require that the
disjoint classes be nonempty.
- Care has to be taken with lists that contain elements of LV.
- Weak OWL only requires the existence of unions, intersections, finite
sets, and complements. This means that (someValuesFrom foo bar) does not
necessarily exist.
- It is not the case that Weak OWL requires IOC to contain all finite
subsets and be closed under union, intersections, and relative
complements. All that is required is that for each such set, IOC
contains an element whose class extension is that set.
- In a Weak OWL interpretation it is not the case that
owl:Thing rdf:type owl:Class .
owl:Nothing rdf:type owl:Class .
In general Weak OWL does not force any particular class to belong to
owl:Class. The claim that owl:Thing, owl:Property, and owl:Class are
analogues to rdfs:Resource, rdfs:Class, and rdf:Property is incorrect.
Further, all of
owl:Class rdfs:subClassOf rdfs:Class .
owl:Restriction rdfs:subClassOf owl:Class .
owl:Property rdfs:subClassOf rdf:Property .
are not true in Weak OWL, nor is
AAA rdf:type owl:Property . -> AAA rdfs:domain owl:Thing .
a valid inference in Weak OWL.
- In Large OWL it is not the case that owl:Class and rdfs:Class have the
same extension. In particular owl:Nothing (and indeed most empty
classes) can belong to neither, either one or, or both of owl:Class and
rdfs:Class in Large OWL. It is thus not the case that IOC=IC or IOP=IP
in Large OWL.
- The closure conditions for Large OWL should change integer to
non-negative integer.
- There are many restrictions in Large OWL that may be problematic because
their presence may affect their extension. For example, what is the
class extension of
_:x owl:onProperty rdfs:subClassOf .
_:x owl:maxCardinality 57 .
Can it be shown that there are *no* problems in determining the class
extensions of all the restrictions that mention the RDF and RDFS
structural properties and that thus may interfere with their own class
extension?
These are all the issues that I could find in a quick partial reading of
the document.
peter
PS: I would much have preferred to try to get a version of the previous
document that didn't have any known bugs before making such drastic
changes.
Received on Monday, 23 September 2002 06:54:17 UTC