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

literals must be self-evident

From: Dan Connolly <connolly@w3.org>
Date: Wed, 17 Oct 2001 12:43:53 -0500
Message-ID: <3BCDC359.7B6E4AB@w3.org>
To: w3c-rdfcore-wg@w3.org
I'm having trouble following the literal model theory
stuff in detail, and my attention is diverted by
stuff like preparation for the upcoming AC meeting,
and I'll be out next week.

But I propose the following requirement as a constraint
on solutions to this literal stuff:

[[[
Lack of ambiguity 

Some programming languages allow one to introduce identifiers
from new name spaces in such a way that it is not possible to
know which namespace a local identifier belongs to without
accessing both the module interface specifications and checking
which one has with the highest priority, or  most recently in the
document, redefined a given local identifier. 

This may have some uses in a programming language such as
Java[Java], but it has a serious flaw in that when one module
changes (without the knowledge of the designers of the other
module), it can unwittingly redefine a local identifier used by the
second module, completely changing the meaning of a previously
written document. Clearly, in the Web world in which modules
evolve but documents must have clearly defined meanings, this is
unacceptable. 
]]]

--        Web Architecture: Extensible languages
http://www.w3.org/TR/NOTE-webarch-extlang#Ambiguity
W3C Note 10 Feb 1998 

That is: it's essential that the interpretation of
an RDF document is a function of the document alone,
and doesn't vary according to the contents of other
documents.

Any solution where the truth/falsehood of a document
(in some interpretation) depends on some range
contraint in another document would be a violoation
of what I suggest is a core RDF requirement.

I realize the alternatives are ugly... I think
the solution there is to accept that RDF/XML syntax
is ugly and persue XML-schema-based approaches
to getting logical meaning out of less constrained
XML.

Anyway... I'm sorry if this doesn't make any sense;
I hope it does, and I hope the WG can consider
it in making decisions about the model theory for literals.

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 17 October 2001 13:43:56 EDT

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