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RE: comments on the uri note

From: Booth, David (HP Software - Boston) <dbooth@hp.com>
Date: Mon, 5 Nov 2007 17:30:52 +0000
To: Peter Ansell <ansell.peter@gmail.com>, Jonathan Rees <jar@creativecommons.org>, "public-semweb-lifesci@w3.org" <public-semweb-lifesci@w3.org>
CC: Michel_Dumontier <Michel_Dumontier@carleton.ca>, "naty.vr@gmail.com" <naty.vr@gmail.com>, "p.roe@qut.edu.au" <p.roe@qut.edu.au>, "j.hogan@qut.edu.au" <j.hogan@qut.edu.au>
Message-ID: <184112FE564ADF4F8F9C3FA01AE50009D36AA16B4C@G1W0486.americas.hpqcorp.net>

Peter,

> From: Peter Ansell
> [ . .. . ]
> Suppose two people come up with slightly different, but mutually
> useful, definitions at the same time and, before an authority has
> declared them to be the same, want to use both of the definitions  in
> queries, and advertise them so they can be used by other users. In my
> view, they would simply add an owl:sameAs statement to their
> definitions to give users the impression that they were infact agreed
> to be the same subject resource.

That's a good example to examine.  To make this more concrete, let's assume these two people mint different URIs U1 and U2 as names for resources R1 and R2, and assume that even though R1 and R2 are very similar, they are slightly different, i.e., there exists a predicate P such that P(R1) is true but P(R2) is false.

For many applications, the difference between R1 and R2 may not matter.  Thus, for many applications it may be perfectly fine and very useful to assert U1 owl:sameAs U2, even though it is not entirely true.  So the problem is that if the assertion "U1 owl:sameAs U2" is made a part of the declaration of U1, then U1 can never be used in situations where the difference between R1 and R2 *does* matter.  Thus, it limits the reusability of U1.

What can the owner of U1 do instead?   The declaration of U1 can provide a seeAlso to a separate document -- not a part of the URI declaration for U1 -- that either asserts U1 owl:sameAs U2 (and perhaps explains that this isn't strictly true), or indicates more specifically the relationship between R1 and R2, such as something like U1 skos:broader U2.

>
> The concept of one-uri-to-rule-them-all portrays the actual situation
> as being very simple, and relies on a single authority for each
> subject area who reviews definitions before allowing them to be used.

I'm not entirely sure I know what you mean by "one-uri-to-rule-them-all", but if you are talking about the idea that (a) URIs should be reused, and (b) usage should be consistent with the URI's declaration, then this does *not* rely on a single authority for each subject area.  It relies on a single "authority" for each URI, but that "authority" is only the authority to say what resource the URI denotes.  It has nothing to do with whether someone is an authority in a subject area.  See the WebArch discussion of URI ownership:
http://www.w3.org/TR/webarch/#uri-ownership
and my document about URI declaration:
http://dbooth.org/2007/uri-decl/

> If one wishes to use this approach then it should be okay, but the
> note should allow for the fact that people will want to change
> definitions as they see fit, even feeling strongly enough about their
> changes or extensions to refer to them as being of the level of an
> authority. Its a dangerous world when people can do anything without
> an authority reviewing everything.
>
> > A seeAlso does not constitute an assertion that you should believe
> > what's at the other end. That would be reserved for something
> > stronger like owl:imports (if I understand it correctly).
>
> Why would you implicitly not want to believe what is on the other end
> of a seeAlso statement? If the author has thought to include it, then
> they think there is some value in it. According to the plaintext
> comment for seeAlso, it declares that "Further information about the
> subject resource." can be found at the target resource. It really
> depends on whether you are interested in further information, or
> whether you want to restrict yourself to the original "defining" set
> of statements.

The reason you might not want to believe what is on the other end of a seeAlso statement is because it may conflict with some other statements that you wish to use.  Suppose the declaration of URI U says to seeAlso documents documents, A, B and C.  Each of these may have very useful information, and may not (individually) conflict with the declaration of U.  But if A and B are used together, there may be a contradiction.  And even though C does not currently conflict with anything, at some later point a new document D might be pulished such that if C and C were used together there would be a contradiction.

The point is that even though these documents may contain useful information, they should be separable from the declaration of U in order to maximize the reuse potential of U.



David Booth, Ph.D.
HP Software
+1 617 629 8881 office  |  dbooth@hp.com
http://www.hp.com/go/software

Opinions expressed herein are those of the author and do not represent the official views of HP unless explicitly stated otherwise.
Received on Monday, 5 November 2007 18:42:38 GMT

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