W3C home > Mailing lists > Public > www-rdf-interest@w3.org > February 2001

Literals and URIs (1)

From: Graham Klyne <GK@NineByNine.org>
Date: Thu, 15 Feb 2001 09:13:59 +0000
Message-Id: <5.0.2.1.2.20010215085723.0366a320@joy.songbird.com>
To: "Bill de hOra" <bill@dehora.fsnet.co.uk>
Cc: "RDF interest group" <www-rdf-interest@w3.org>
Bill,

I think this is an important issue you raise, but one that I was trying not 
to invoke in this context.

My own view is that the literal, of itself, does not carry any of the other 
information you imply.  "Paris" is just a string of 5 characters.  In 
different contexts it may be used to stand for different ideas, such as the 
city, the god, the perfume, etc.  Converting the string to a data: URI 
doesn't change that.

IMO, when a literal is "converted" to a resource, the resource represents 
only the literal, not some resource that is described or named by the 
literal.   Any deeper associated meaning is conveyed by the context, not by 
the literal or resource itself.

I think that when one tries to attach other meaning to the literal itself, 
or its corresponding resource, one gets into the kind of difficulties that 
you raise here.

#g
--

At 10:50 PM 2/14/01 +0000, Bill de hOra wrote:

>: Graham Klyne:
>:
>: Should there be exactly one resource corresponding to a given literal, or
>: may there be many?
>
>It does not seem sound to unify literals by conveting them to URIs. Any such
>attempt is to say the least, lossy. Converting a literal to a data URI doesn't
>give any more information about the literal that would allow it to be matched.
>Consider a trivial example:
>
>"Paris" -> data:,Paris
>"Paris" -> data:,Paris
>"Paris" -> data:,Paris
>
>The first "Paris" was the name of a perfume, the second was the name of a god,
>the third was the name of a city. By converting them all to URIs, I've lost
>information. If I convert them to different URIs I add no information. One way
>to gather information is via the local context in which these were found, so a
>machine might be able to abduct with a reasonable probability that as it
>happens:
>
>"Paris" -> data:,ParisTheCity
>"Paris" -> data:,ParisTheGod
>"Paris" -> data:,ParisThePerfumeTM
>
>Of course the machine will have to make a best effort attempt to do this for
>each and every occurence of "Paris", there's no chance of a general search and
>replace. The machine might get the mappings wrong. But so do people.
>
>Yes it is annoying that literals can't be matched in a general way, but that's
>not a problem unusual to RDF, and no one here should be expecting the wg 
>or the
>ig to solve it by URI hacking. We could disallow the literals altogether, but
>that's not really practical. One suggestion would be that the next M&S
>explicitly acknowledege this limitation in using literals and suggest
>non-normatively and in the nicest possible way, that people who want to
>interoperate and allow their data to be inferred over by others ought to 
>ground
>it and stop being so lazy :)
>
>Bill de hOra

------------
Graham Klyne
(GK@ACM.ORG)
Received on Thursday, 15 February 2001 05:11:49 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:51:48 GMT