Hi Kenny,
I am inclined towards your position that ontologies (and some other
resources) don't require a distinction between the entity and the
specification, because the representation being served is the entity
in the case of an ontology.
In general I think both practices are acceptable. If anybody knows of
any compatibility problems caused by using an empty hash as the URI
reference for the ontology, it would be good to raise his/her voice,
though.
The most important point is that the identifier used for the ontology
(owl:Ontology) should be the same as the one used for the
rdfs:isDefinedBy property.
Best
Martin
On 21.10.2010, at 17:05, KangHao Lu (Kenny) wrote:
Hello Martin,
I don't think my argument would be very logical, but we can't wait
for rule engines to discuss this.
Note, however, the majority of the Web vocabularies use the same
URI for the entity name reference and the descriptor reference, see
the link provided by Michael Hausenblas:
http://code.google.com/p/void-impl/issues/detail?id=45
and in particular the little survey by Richard Cyganiak posted on
that page.
I personally would argue that in the case of ontologies /
vocabularies, the conceptual difference between the entity and the
descriptor is a lot less significant than when it comes to data,
since an ontology is, by definition, a specification, i.e. a
document.
Basically I like this approach, that is, I don't like the fact that
some ontologies have '#' as end character and there should not a URI
for an ontology document and a different URI for the *conceptual*
ontology.
IIRC, 3 years ago Tim was very shocked by those ontologies that have
'#' as end charter and claimed that this is not a good idea (and he
would bring up this issue at TAG or awwaw, I can't remember). The
argument was that string after '#' has the meaning of 'local
identifier' (so that we use #I #i for WebIDs because 'I' is a 'local
identifier') and identifiers can't be empty strings (or this might
break some systems, I guess). I somehow agree with that, and Toby's
use of "my:" to identify an Ontology makes me a little bit
uncomfortable. I have no idea if there's any followup after Tim
brought this to TAG or awwaw.
I have another argument, namely, you should distinguish the concept
from the document only if the following criterion is satisfied.
- if the time when the thing with hash URI is created and the time
when the document is created have *clear* difference
So this holds for people, so people should not use document URIs.
This holds for organizations, cause you create the website of an
organization maybe some years after the organization is founded.
The problem is 'ontology'. I don't know whether you should call the
structure an ontology or it became an ontology once it is written
down, but I don't think the difference of the timing is very
*clear*. A similar example is when you want to give a URI to a
python module. I would not end it with '#' because I don't see why
we need do distinguish the 'module document' from 'module'. A module
is a kind of document, so is ontology. So, owl:Ontology
rdfs:subClassOf foaf:Document !
Well, this is a theory. If there's a common practice of using '#'-
ending URI for ontologies, maybe we should accept it.
No strong opinion. Wasn't this discussed at AWWAW? Just curious.
Cheers,
--
Kenny
WebID: http://dig.csail.mit.edu/People/kennyluck#I
What is WebID: http://esw.w3.org/WebID