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Re: literals that do not have a single pre-speficied meaning

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 09 Oct 2001 11:38:10 -0400
Message-ID: <3BC319E2.4DDD3A09@research.bell-labs.com>
To: w3c-rdfcore-wg@w3.org
> Re: Comments on ioctl (was: Re: big issue (2001-09-28#13))
> 
> From: Pat Hayes (phayes@ai.uwf.edu)
> Date: Mon, Oct 08 2001
> 

> Which, by the way, is exactly what Peter Patel-Schneider is currently
> roasting my feet over the fire about, for exactly the reason you
> raise: he doesn't want literals to be forced to have a single global
> meaning in DAML. If I thought that 'literal' meant simply 'character
> string'. I would agree with him (and I suspect, you), but I have
> never thought that it did mean that. Maybe I was wrong, though, in
> this community; and if so, then I should probably change the model
> theory, or at least the way it is worded. 

> However, if literals really
> are just character strings, then I don't really see any coherent way
> of allowing a single bare character string to have a number of
> different literal values. If "20001225" really could mean either a
> bit more than 20 million or Xmas day, surely *something* has to be
> able to decide which one is meant, when one comes across that string
> in a graph somewhere?

The model-theoretic semantics for DAML+OIL (March 2001) allows for bare
character strings to have a number of different literal values.  (I also
have a newer version of that basic semantics, which I will post shortly,
that directly addresses RDF and RDF Schema.)

The basic idea is to allow literals to denote any of the literal values
for which they are a lexicalization, as determined by the collection of
datatypes (a la XML Schema).  (Of course a particular interpretation has
to have only one of these possibilities.)  When (and if) type
information is available, this ambiguity is resolved.

One might argue that my scheme is wrong for philosophical reasons, but
it is possible technically.  (At least I think so.)

> Pat

Peter F. Patel-Schneider
Received on Tuesday, 9 October 2001 11:33:38 EDT

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