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Re: OWL and Published Subjects

From: Jim Hendler <hendler@cs.umd.edu>
Date: Thu, 19 Jun 2003 19:24:45 -0400
Message-Id: <p05200f28bb17f5cc8a59@[]>
To: "Bernard Vatant" <bernard.vatant@mondeca.com>, "Public-Webont-Comments@W3. Org" <public-webont-comments@w3.org>

At 5:36 PM +0200 5/6/03, Bernard Vatant wrote:
>Please find below some comments about expected interoperability of OWL,
>Topic Maps in general and Published Subjects in particular.

Bernard - thanks for these comments - we are very pleased to learn 
that OWL meets the requirements for Published Subjects.  We believe 
that no changes to OWL are requested below, could you confirm that or 
let us know if you have concerns that we haven't addressed
  -Jim H.
p.s. Speaking for myself, not as a representative of the WG, I like 
the idea of some sort of PSI-in-OWL document, and would like to 
discuss this with you offline when time permits.

>Disclaimer : Those comments are engaging only their author, and must not be
>considered as "official" feedback neither from the Topic Maps standard
>working group (namely ISO/IEC JTC1/SC34-WG3), nor from the OASIS Published
>Subjects TC that I happen to chair. Interoperability with OWL has not been
>put on the agenda of those groups so far. That is something I personally
>deplore, and that seems due to many reasons, among which: lack of task
>force, "not developed here" syndrom, and last but least lack of formal
>foundation for Topic Maps, making the whole TM community uneasy about the
>Before going to the specific point of Published Subjects, I want to say
>that I have been working for some time now, on an OWL expression for Topic
>Maps, trying to consider them as some specific kind of ontology - which I
>think it should be, no more, no less. Although TM gurus have always claimed
>them to be ontology-neutral, this is IMO wrong, the only way to be
>ontology-neutral being to keep silent. And Topic Maps folks are known to be
>very talkative :)
>Difficulties that I meet to achieve that task seem to come, not from the
>lack of expressive power of OWL, but from the lack of consensus for what
>are the foundations of Topic Maps, default a consensus on their formal
>model. "What is a topic map?" is still an open issue it seems. A good
>reference for the state of reflection in TM community vs RDF and OWL is the
>paper from Lars Marius Garshol "Living with Topic Maps and RDF" that he
>will present this week at XML Europe:
>Concerning Published Subjects, I will show below that OWL documents could
>easily meet the Requirements and Recommendations for Published Subjects
>expressed in Deliverable 1 of OASIS PubSubj TC [1], about to be adopted as
>a TC specification (hopefully) in London next Friday:
>- Requirement 1:
>"A Published Subject Identifier must be a URI."
>Sor far, so good. Any URI identifying an OWL class, property or individual
>can be used as a Subject Identifier.
>- Requirement 2:
>"A Published Subject Identifier must resolve to an human-interpretable
>Published Subject Indicator."
>Are OWL ontologies human-interpretable? Depending on humans, of course. But
>providing sensible use of labels and comments, an OWL element can be a very
>accurate Subject Indicator for the class, property, or individual it
>- Requirement 3:
>"A Published Subject Indicator must explicitly state the unique URI that is
>to be used as its Published Subject Identifier."
>This is more tricky. Take for example
>Extracted from an attempt of re-writing a DAML university ontology in OWL)
><owl:Class rdf:ID="Employee">
>   <owl:sameAs
>rdf:resource="http://www.mondeca.com/owl/general1_0.xml#Employee" />
>Here both http://www.mondeca.com/owl/univ1_0.xml#Employee and
>http://www.mondeca.com/owl/general1_0.xml#Employee could be valid subject
>identifiers. So, to be conformant to Requirement 3, either a general rule
>should be set, or a specific explicit property should be set like
>psi:identifier, in the following way.
><owl:Class rdf:ID="Employee">
>     <owl:sameAs
>rdf:resource="http://www.mondeca.com/owl/general1_0.xml#Employee" />
>     <psi:identifier
>rdf:resource="http://www.mondeca.com/owl/univ1_0.xml#Employee" />
>This is to be discussed and settled, but the expressive power is here. Note
>that the "sameAs" declaration leads to the important notion of equivalent
>identifiers. A topic map application should be able to make sense of it by
>aggregating on a single topic node its various subject identifiers in
>various ontologies.
>- Recommendation 1:
>"A Published Subject Indicator should provide human-readable metadata about
>This can be achieved by using specific DatatypeProperties, either at the
>element level or at the ontology level, like the dc elements that can be
>found in the above quoted ontology. Note that the TC has not decided yet
>what kind of metadata are relevant, but there again the expressive power of
>OWL can support a large variety of those.
>- Recommendation 2:
>"A Published Subject Indicator may provide machine-processable metadata
>about itself."
>No comment here. Metadata expressed in OWL are obviously
>- Recommendation 3:
>"Metadata defined in Recommendations 1 and 2 should be consistent, but need
>not necessarily be equivalent."
>I figure human-readable metadata here being only a transcription of OWL
>information in a more human-readable format than rdf.
>- Recommendation 4:
>"A Published Subject Indicator should indicate that it is intended to be
>used as a PSI."
>This can be specified in the ontology header.
>- Recommendation 5:
>A Published Subject Indicator should identify its publisher.
>There again this information can be included in the ontology header.
>In conclusion, I consider OWL as a very convenient format for expression of
>Published Subjects. Moreover, providing the few points quoted below are
>cleraly settled, it could be possible to have a recommendation for
>"PSI-in-OWL", approved both by OASIS PubSubj TC as conformant to its
>Requirements and Recommendations, and by OWL-WG as a recommended
>application of OWL.
>Again, I insist this is only so far a personal roadmap, I will put it on
>the OASIS PubSubj TC agenda and see what happens there, and it's up to
>OWL-WG to see if it also fits iis agenda.
>Thanks for your attention
>Bernard Vatant
>Senior Consultant
>Knowledge Engineering
>Mondeca - www.mondeca.com
>[1] Complete archives of PubSubj TC work are temporarily at
>The official OASIS TC site is under reconstruction, due to CMS migration,

Professor James Hendler				  hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  *** 240-277-3388 (Cell)
http://www.cs.umd.edu/users/hendler      *** NOTE CHANGED CELL NUMBER ***
Received on Thursday, 19 June 2003 19:24:50 UTC

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