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RE: silly question about rdf:about

From: Joshua Allen <joshuaa@microsoft.com>
Date: Thu, 11 Apr 2002 21:24:59 -0700
Message-ID: <4F4182C71C1FDD4BA0937A7EB7B8B4C104D1C6AF@red-msg-08.redmond.corp.microsoft.com>
To: <LMM@acm.org>, <uri@w3.org>
> If you leave netcrucible, someone else named Joshua Aardvaark joins
and
> puts up http://www.netcrucible.com/people/joshuaa, it's a different
> person.

Right, that is what my UAW example was showing.  I'm simply pointing out
that a date is not terribly useful for disambiguation (well, actually I
don't know exactly what the date is useful for).

> Maybe it's reasonable -- and maybe not -- to treat two tdbs which
differ
> by a small date range to be 'the same'.

I can accept this.

> Can I post your comments & my reply on the 'uri@w3.org' list?

Done :-)

Thanks,
Joshua

> -----Original Message-----
> From: Larry Masinter [mailto:LMM@acm.org]
> Sent: Thursday, April 11, 2002 5:19 PM
> To: Joshua Allen
> 
> I think that the problem of persistence of identity is really
difficult --
> it's one of those problems like "is the morning star the same as the
> evening star", because, after all, they appear at different times. And
> with 'tdb', there are two kinds of ways in which meaning can vary over
> time: (a) the web resource itself could change (the corresponding
urn:duri
> might yield a different document), and (b) the understanding of what's
> being described might change.
> 
> If you leave netcrucible, someone else named Joshua Aardvaark joins
and
> puts up  http://www.netcrucible.com/people/joshuaa, it's a different
> person.
> 
> I don't think you can assume there are unique identifiers for people
(or
> anything else), unless you choose a narrower domain of identification
that
> tries to assure that each 'thing' only gets one identity, e.g.,
identify
> you by your SSN or some other country's national identity number.
> 
> In the end, a meta-indexer has to use heuristics to decide whether two
> identified resources are the 'same' for the purpose of the indexer's
index.
> Maybe it's reasonable -- and maybe not -- to treat two tdbs which
differ
> by a small date range to be 'the same'.
> 
> I think this is completely orthogonal to the issue of media
representation,
> which includes a wide range of variability, not just MIME type.
> 
> I don't think 'tdb' or 'duri' are useful in situations where there is
a
> 'client' and 'servers' and you're trying to do content negotiation. It
> doesn't really help with that.
> 
> Can I post your comments & my reply on the 'uri@w3.org' list?
> 
> 
> 
> 	-----Original Message-----
> 	From: Joshua Allen [mailto:joshuaa@microsoft.com]
> 	Sent: Monday, April 08, 2002 11:49 PM
> 	To: LMM@acm.org
> 	Subject: RE: silly question about rdf:about
> 
> 
> 	Yeah, I read this last night when Aaron posted about it on
#rdfig.
> I like the idea of a tdb URI scheme, but I am uneasy about putting a
date
> into a tdb.  The section 5.6 comment applies more to duri than tdb;
that
> is, one would expect that the thing being described would still be the
> same thing after a period of time.  That is, the two URIs:
> 
> 	urn:tdb:2001:http://www.netcrucible.com/people/joshuaa
> 	urn:tdb:2002:http://www.netcrucible.com/people/joshuaa
> 
> 	are different URIs, but most likely identify the same "thing".
> The fact that the URIs are different would complicate (but not
prevent)
> attempts to index assertions about a particular "thing".
> 
> 	An example of where the date would be useful would be something
like:
> 
> 	urn:tdb:1996:http://www.uaw.org/officers/president
> 	urn:tdb:2002:http://www.uaw.org/officers/president
> 
> 	Which do describe different things.  But even then, a metadata
> indexer is left with two choices -- you either index all data for each
> distinct date as if they describe different "things", or index them as
if
> they all describe the same thing.  Either option is unlikely to give
> accurate metadata aggregation.  In other words, the date is relatively
> useless to disambiguate the tdb, so other techniques would have to be
used.
> 
> 	So, I believe that the tdb scheme would be useful to divert
people
> who insist on saying that an HTTP URI represents more than just a
document.
> For that alone, it would be nice.  There would of course still be the
"One
> HTTP URL can represent many different resources by use of a mime-type"
> arguments, so those would need to be put to rest somehow.  And beyond
that,
> I am still trying to think of places where I would want to use the
duri
> (non-tdb).  At first glance, it seems appealing; a sort of
metadata-safe
> way to do HTTP etags.  But etags are most useful when maintained by
the
> server, and not by the client -- I think the same would be true of the
> datepart in tdb and duri -- but in the case of tdb and duri, if a
server
> is going to go through the trouble of updating the datepart of the URN
> every time that a resource change (or change of president at the UAW)
> requires, then the server might as well just assign a new URN.  So I
am
> still trying to get the use cases.
> 
> 
> 
> 		-----Original Message-----
> 		From: Larry Masinter [mailto:LMM@acm.org]
> 		Sent: Mon 4/8/2002 9:01 PM
> 		To: Joshua Allen
> 		Cc:
> 		Subject: RE: silly question about rdf:about
> 
> 
> 
> 		> The most important thing to me, by far, is just to
have a
> decision and
> 		> get rid of the uncertainty.  I wish someone would just
> declare that
> 		> "this is how URI's for identity work, and all other
ways are
> 		> discouraged."
> 
> 		How about "tdb" in
> http://larry.masinter.net/duri.[html,txt,xml] ?
> 
> 
Received on Friday, 12 April 2002 00:25:32 GMT

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