From: Dan Connolly (connolly@w3.org)
Date: 10/02/01
"Peter F. Patel-Schneider" wrote:
>
> > [Dan Connolly]
> > >It's also possible to design a language where the type of
> > >a literal may *depend* on a declaration from an XML schema:
> > >
> > > <kr:KRLang xmlns:rdf="http://...new-kr-lang..."
> > > xmlns:ex="http://example/vocab">
> > > <ex:Person>
> > > <ex:name>John Doe</ex:name>
> > > <ex:shoeSize>10</ex:shoeSize>
> > > </ex:Person>
> > >
> > >so that the "10" above is not a logical constant at all;
> > >not until you find a/the schema for http://example/vocab
> > >do you know how to parse/interpret "10"... i.e. the
> > >meaning of that chunk of XML is dependent on all the
> > >trust issues around following links from one document
> > >to another (not to mention a complete implementation
> > >of XML Schema, an effort several orders of magnitude
> > >larger than an RDF 1.0 parser).
> > >
> > >This sort of language is not a candidate for a future
> > >version of RDF: it fails to meet
> > >one of the basic requirements of RDF: that an RDF document
> > >stands on its own as a logical formula.
>
> I fail to see how this follows.
I'm not sure I can explain it any better. Maybe Pat H. can;
he seems to have understood.
> I would also appreciate a pointer that provides some measure of support for
> the premise of this inference. (In fact, I would find it very instructive
> to see a concise, authoritative enumeration of the ``basic requirements of
> RDF''.)
Er... I'm not sure what sort of authority you're after.
The RDF Model & Syntax WG didn't make requirements part
of the 1.0 spec.
This excerpt is from a NOTE that has no formal standing,
but perhaps you'd find it convincing regardless of the source...
[[[
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
Perhaps you would find a statement from one of the RDF 1.0 editors
compelling:
"This is indeed an explicit a design decision ..."
-- Ora to www-rdf-logic Mon, 01 Oct 2001 04:28:11 -0400
As to concise, I condense the design principles of RDF
as follows when I present it:
[[[
Semantic Web
Principles
terms grounded in URI space
simple XML usage for use with XSLT etc.
explicit translation to statements
natural language statements
logical formulas
]]]
-- http://www.w3.org/2001/Talks/0103daml-kt/slide7-0.html
--
Dan Connolly, W3C http://www.w3.org/People/Connolly/
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