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RE: Calling the rdf file an ontology?

From: Reto Bachmann-Gmür <reto@gmuer.ch>
Date: Fri, 13 Jul 2007 22:33:10 +0200
To: Yoshio Fukushige <fukushige.yoshio@jp.panasonic.com>
Cc: semantic-web@w3.org
Message-ID: <h1Ptwhr4LVxx.HXGGCD4Z@smtp.mxes.net>

Hi Yoshio

I think that an ontology can be seen as an information resource an thus have a derefernceable http-uri as its name (some ontolgies have a trailing pound sign, which may indicate that they authors consider an ontology as something more abstract than an information resource). An rdf/xml document is just one representation of an ontology, I would assume a URI ending with .rdf to name such a representation rather than the ontology itself. The ontology can savely have different representations targetted for humans (xhtml, pdf, etc.) or machines (different rdf serialization).

If  <http://ont.example.org/myOnt/example> is a owl:Class then a webserver would have to return a 303 response since a class is not an information resource.

An approach for your single-term ontologies would be:
<http://ont.example.org/myOnt/example> rdf:type owl:Ontology.
<http://ont.example.org/myOnt/example#> rdf:type owl:Class.
It is however a bit unconventional to have a trailing pound-sign at the end of the name of a class, as this usually separates the name of the ontology from the local name of the term. Also this approach doesn't allow graphs using these ontologies to make a very effective use of namespaces when serialized as rdf/xml or n3.

If your concern is that one should be able to get a description of a term without having to download a huge ontology I would rather use URIs like

http://example.org/myOnt/myClass

for an individual class, and configure the webserver to send a 303 pointing to

http://example.org/myOnt/myClass-description

which dereferences to some rdf containing the description of the class inclusing the triple

<http://example.org/myOnt/myClass> rdfs:isDefinedBy <http://example.org/myOnt>.

http://example.org/myOnt would dereference to the whole ontology but a typical way to retrieve the definition of a single term wouldn't require to download this huge thing.

reto

- original message -
Subject:	Calling the rdf file an ontology?
From:	Yoshio Fukushige <fukushige.yoshio@jp.panasonic.com>
Date:		11/07/2007 10:40


Hi all,

I have two questions on what should be called as owl:Ontology.

(1)
Let's assume we have the following assertion:

<http://ont.example.org/myOnt/example> rdf:type owl:Ontology.  ...(A)

Now if the vocabulary is defined in http://ont.example.org/myOnt/example.rdf,
and what is retrieved by 

GET /myOnt/example HTTP/1.1
Host: ont.example.org
Accept: application/rdf+xml

is http://ont.example.org/myOnt/example.rdf,

then does the following make sense and mean the same thing as (A)?

<http://ont.example.org/myOnt/example.rdf> rdf:type owl:Ontology.  ...(B)

If (A) and (B) mean different things, then which should we use in this situation?

Will the decision change if one receives its accompanying html document
(example.html) by 

GET /myOnt/example HTTP/1.1
Host: ont.example.org
Accept: text/html

or

GET /myOnt/example HTTP/1.1
Host: ont.example.org
Accept: application/xhtml+xml

?

(2)
If (A) and (B) above mean different things, does the following make any sense?

-----
<rdf:RDF xmlns="http://www.w3.org/2002/07/owl#"
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">

    <Ontology rdf:about="http://ont.example.org/myOnt/example.rdf"/>

    <Class rdf:about="http://ont.example.org/myOnt/example"/>

</rdf:RDF>
-----
(this should be in /myOnt/example.rdf )

What I want to do is to put each terms in the vocabulary in mind
into separate files defining only that term and name the file 
after the term name. But I want to remain in DL.
That's why I don't write

    <Ontology rdf:about="http://ont.example.org/myOnt/example"/>

in the example above (to separate the Class name from Ontology name).

Is that so weird a practice?

-- 
Yoshio Fukushige <fukushige.yoshio@jp.panasonic.com>
Network Development Center,
Matsushita Electric Industrial Co., Ltd.
Received on Friday, 13 July 2007 20:33:15 UTC

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