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Re: assymetric reference of properties

From: martin <martin@csi.forth.gr>
Date: Fri, 28 Jan 2000 11:15:00 +0200
Message-ID: <38915E14.39FB22B4@ics.forth.gr>
To: Eric Hellman <eric@openly.com>
CC: www-rdf-interest@w3.org
Dear Eric,

Actually it is my proposal to keep the "inverse" property out of rdfs as
an independent item.
As it stands now, the use of RDFS lets no other choice than to duplicate
each property. This should be avoided. Our proposal is, to assign to
each
property two names, a forward and a backward one. But any other
mechanism 
identifying pairs of inverse properties or using an inverse of one
property
would be helpful. Two names are more userfriendly. To interpret things
like
"has created -1" as "was created by" or "was made for -1" as "was
intended use of"
can be confusing. Often double naming is already a reality from other
sources,
as e.g. http://purl.org/dc/documents/wd-relation-current.htm, the Dublin
Core
relation types. Putting only one name in RDFS would give raise to hard
decisions,
which relation name to delete.

Eric Hellman wrote:
> 
> We encountered the same situation in our linking metadata schema. A
> lot of code was expended making sure that we don't get stuck in
> endless loops while traversing models with these reciprocal
> relationships- probably its a good excuse to keep the "inverse"
> property out of rdfs. But I certainly agree that it's a needed
> facility at some level.
> 
> Eric
> 
> At 11:48 AM +0200 1/26/00, martin wrote:
> >Dear collegues,
> 
> <stuff deleted>
> 
> >In the CRM we have foreseen an "inverse name" for all data models, which
> >do have the above problem. I.e. as convenient, users may either use
> >the name "is identified by" for the property in the first example,
> >or the name "identifies" for the its inverse. The simultaneous provision
> >of both links as above, without further formal semantics, seems not
> >to be very satisfactory.
> >
> >I can imagine 3 solutions:
> >
> >a) A statement is introduced in RDFS, stating that property B is the
> >    inverse of property A. This would allow at least to formally exchange
> >    information about the inverse equivalence of A and B.
> >b) RDF descriptions are extended to declare property instances of the
> >    inverse of a property type. This would avoid double declaration,
> >    lead to redundance-free models, but make an arbitrary decision to
> >    from where the "original" property is read. The use of the inverse
> >    property type becomes less comprehensive to read for humans.
> >c) RDFS is extended to register two names for each property, a forward
> >    and a backward one, as we propose in the CRM, and RDF descriptions
> >    allow for either use according to the direction of use. The latter
> >    seems to us the most appropriate solution.
> >
> >Comments welcome.
> >
> >Martin Doerr
> 
> Eric Hellman
> Openly Informatics, Inc.
> http://www.openly.com/           21st Century Information Infrastructure
> LinkBaton: Your Shortcuts to Information  http://linkbaton.com/

-- 

--------------------------------------------------------------
 Dr. Martin Doerr              |  Vox:+30(81)391625          |
 Senior Researcher             |  Fax:+30(81)391609          |
 Project Leader SIS            |  Email: martin@ics.forth.gr |
                                                             |
  Centre for Cultural Informatics and Documentation Systems  |
                Institute of Computer Science                |
   Foundation for Research and Technology - Hellas (FORTH)   |
                                                             |
 Vassilika Vouton,P.O.Box1385,GR71110 Heraklion,Crete,Greece |
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Received on Friday, 28 January 2000 04:11:21 GMT

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