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RE: UBL Naming Conventions & RDF

From: John McClure <jmcclure@hypergrove.com>
Date: Fri, 8 Jul 2005 10:59:36 -0700
To: <semantic-web@w3.org>
Message-ID: <MGEEIEEKKOMOLNHJAHMKIEEGDOAA.jmcclure@hypergrove.com>

Thanks all for the responses.

1. Danny Ayers points out correctly that the same semantic (that X is a
"Person") can be inferred if the 'range' for "hasParent" is a "Person".... true,
but here I'd like to address the implications of the UBL reqt that names of its
elements (particularly, its property names) be nouns, NOT predicates.

2. Ian Davis suggests the alternative <Person> <parent> <Person rdf
about='uri'/> </parent> </Person>
for my <Person><has><Parent rdf about='uri'/></has></Person>. My concern is that
<parent> is a noun, in effect, thereby eliminating predicate verbs as meaningful
classes (for there is <willHave><Parent>, <had><Parent>, and other similar
predicate verbs); that, as a property, it has not the expressiveness of
restrictions, unions, and intersections available via owl:equivalentClass; and
that it lacks the quality of being able to make statements about or establish
membership within 'a set of (all) parents', that is, one cannot say that a
(Person rdf:type Parent).

Ian asks about <foaf:knows>.... while not a master of FOAF, I think the
equivalent expression using predicate nouns would be <Person><has><Acquaintance
rdf:about='uri'/></></>.... surely, one 'knows' one's acquaintances to some
degree.

3. Frank Manola notes that some don't use <hasX> implying he has seen <has><X>
before.... who would they be I am wondering. Other than rdf:type, *all* OWL
property names confabulate the predicate verb with a predicate noun, consistent
with fundamental RDF architecture, Fact=Subject+Predicate. This architecture
clearly results in a "RDF Naming Convention". Frank also states that "the
'hasFoo' approach has the merit of indicating the directionality of the
relationship" a feature which, I believe, is preserved by <has><X>. Like Frank,
I also value readability highly, and therefore am cautious about designs which
eliminate predicate verbs from markup altogether. Frank also suggests I take
this question over to the SWBP list (see below).

-------------------
Why is this issue more than just a syntactic game? My problem stems from the
fact that domains (and ranges) can be specified only for properties, not for
classes. These nouns indicate sets of Things; they are undoubtedly classes. But,
how does one specify that for instance, only a LivingThing can have a Parent?
One cannot with OWL DL, but of course in OWL Full, I can create metaclasses such
as Noun (subClassOf Class), Verb and Preposition (subClassOf Property), and
DirectObject (subClassOf Noun and subClassOfProperty). Then, define 'Parent' as
an instance of a Noun (and subClassOf Role), and define 'CustodialParent' and
'BiologicalParent' as instances of DirectObject, with range (or subClassOf)
'Parent' and with domain (sic) Person. This yields what to me is a most sensible
statement: <Person><has><CustodialParent rdf:about='uri'/></></>.

In other words, the architecture is that the name of the direct object is
*never* a type of object (Parent) but rather it is *always* its functional role
with respect to the subject of the 'statement' being made. Here, CustodialParent
reflects the role that a Parent plays with respect to the Person. Note also that
CustodialParent can easily function anonymously....
<Person><CustodialParent/></Person> can imply the <has> predicate verb. Finally,
note that the range for <has> is flaccid: it is just a DirectObject.

So the conclusions I'm presently drawing are
(1) it is not  possible to create a UBL conforming ontology using OWL Lite or
OWL DL
(2) in OWL Full, a grammatical foundation is both feasible and immediately
useful

With regard to the suggestion that this be handled by SWBP, I would be fine
doing so but am wondering also whether the matter that RDF has yet to define
constructs like <Noun>, <Verb>, and <DirectObject> has traction here in
semantic-web, since I'd think the reach of the SW would be considerably greater
should UBL requirements be accommodated as soon as possible. *RDF Naming
Conventions* is clearly a ripe issue for SWBP but your concurrence with (1) and
(2) above would provide excellent guidance for that discussion.

Thanks,
John McClure

PS I admit to being 'just' an XML guy, so please bear with me if I mangle any N3
expressions!
Received on Friday, 8 July 2005 17:59:30 UTC

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