[Person-ontology] first contributions - is the Higgins top-level useful?(TYPO)

[Pat Hayes]

Sorry, a line got elided from this  email, making it 
incomprehensible. Corrected below.

>Let me try to put this into actual RDF/XML based on higgins.owl
>
><higgins:DigitalSubject rdf:about="urn:adam">
>    <hasHairColor rdf:resource="urn:value1">
></higgins:DigitalSubject>
><higgins:String rdf:about="urn:value1">
>    <higgins:string>blond</higgins:string>
>    <higgins:source>DMV</higgins:source>   <!--
>This is a simplification, "source" should
>actually have a SubjectRelation as value -->
>    <higgins:expires>Jan 1, 2010</higgins:expires>
></higgins:String>
>
>So while it is true that strictly speaking the
>metadata (expires, source) is applied to value1
>instead of the whole statement, it really
>doesn't matter, since value1 is only used as the
>value of a single statement.

Two points. First, this is a very fragile and
error-prone way to build an ontology, since you
are relying heavily on what in RDF is a syntactic
accident with no semantic meaning. This will work
for a while if you are very careful, but it will
almost certainly break when you start trying to
do nontrivial inferencing (in RDFS, certainly in
OWL). No conforming tools will be able to tell
you the source of the bugs that arise, since they
will not know your idiosyncratic conventions.

Second, it does matter, since the 'value' is
asserted to be the object of the property
hasHairColor. Tell me now, please, what the range
of hasHairColor is? It is apparently not hair
colors; it is strange entities which have
associated dates and information sources, which
apply to the assertion in which the value occurs.
But how far 'out' do these dates and other
properties extend? Suppose what I have to record is
best described using a piece of OWL - say, a
property restriction - which when mapped back
into OWL/RDF becomes a small RDF subgraph rather
than a single triple. How do I know to which
triples in a larger graph the dates attached to a
value are meant to apply?

With the greatest respect, the only way I would
describe the Higgins ontology is
<string>broken</string>. It is trying to graft an
alien conceptual framework into RDF in a way that
does not naturally fit. The fact that the entire
XML Schema datatype system had to be reified
should have been a red flag that something wasn't
going correctly.

Pat Hayes

-- 
---------------------------------------------------------------------
IHMC		(850)434 8903 or (650)494 3973   home
40 South Alcaniz St.	(850)202 4416   office
Pensacola			(850)202 4440   fax
FL 32502			(850)291 0667    cell
phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes