W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > November 2001

Re: heading toward datatyping telecon

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Mon, 5 Nov 2001 20:01:35 -0600
Message-Id: <p05101031b80cf2f9f8a4@[65.212.118.166]>
To: Patrick.Stickler@nokia.com
Cc: w3c-rdfcore-wg@w3.org
>Literals as subjects don't work because they are just
>ambiguous strings.

No no, that begs the question. The point is that if datatyping 
information is available then the literals are no longer ambiguous. 
But in any case, this is just as much an objection to having them as 
objects as having them as subjects. I can see no rational reason for 
there being any distinction between things allowed in subject and in 
object positions.

>E.g. consider the following simple example:
>
>    "fi" <rdf:type> <urn:iso:3166_1> .
>    "fi" <rdf:type> <urn:iso:3166_1> .
>
>One defines a language, the other a country. Yet these
>get merged into ambigous "knowledge" about the subject "fi".

They should not be merged; it is important to keep literal nodes 
distinct for just this reason.

>What is it? A language or a country? Both? How does
>one differentiate between where it denotes *only* the
>country or the language?

By providing datatyping information associated with the literal 
occurrences, which is considerably easier and more natural if they 
are allowed to be subjects, since then it can simply be asserted of 
them directly.

>So, unfortunately, literals as subjects don't work (or at
>least don't scale reliably, beyond very small closed systems).
>
>The problem is that so many folks are used to using strings
>as values, relying on static, native understanding embodied
>in the systems they use, that they keep trying to use strings
>in their knowledge bases, when in fact, in most cases, they
>should be using resources identified by URIs.

Your voice here has the tone of a Baptist minister. I wonder, has it 
ever occurred to you that some knowledge bases might use names 
*other* than URIs? (eg all the knowledge, not to say even data, bases 
that were created before the W3C even invented the term 'uri').

But in any case, we were talking about literals, not strings.

>......
>Whatever we work out with regards to typed data literals, let's also
>perhaps try to find a solution that encourages more useful and
>scalable knowledge representations -- particularly those employing
>controlled vocabularies, and which will (hopefully) encourage folks
>to move away from the problemmatic use of ambiguous strings.

On the contrary, let us not try to cover the world with leather. 
Chances are that other people might have some good reasons for doing 
what they do.

Pat

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Received on Monday, 5 November 2001 21:01:35 EST

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