Hi,
a couple of times now I ran into misunderstandings by students
regarding a common visualization style of property domain/range
relationships in ontologies. Actually, it is quite common to draw
diagrams of ontologies in a style similar to ER diagrams, where
classes are represented as ellipses, and properties that have these
classes as domain/range are represented as arcs between these ellipses
(e.g. [1], which is meant to describe the domain and range for
foaf:holdsAccount).
However many "newbies" to RDF and ontologies are confused by this,
because the triple
foaf:Agent foaf:holdsAccount foaf:OnlineAccount .
is actually not contained in the ontology. It's hard to explain them
the difference between this way of representing ontologies and the
graphical representation of the actual triples. Thus I ask everyone to
reconsider the way you visualize ontologies in publications,
tutorials, etc. to make them consistent with the "normal" way of
graphical RDF notation.
[1] <http://www.ifs.univie.ac.at/schandl/2009/06/domain+range_bad.png>
[2] <http://www.ifs.univie.ac.at/schandl/2009/06/domain
+range_better.png>
Best,
Bernhard
