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TDL conflicts with the "duh!" requirement

From: Dan Connolly <connolly@w3.org>
Date: 25 Jan 2002 10:27:34 -0600
To: RDF core WG <w3c-rdfcore-wg@w3.org>
Message-Id: <1011976054.2608.116.camel@dirk>
Brace yourself for mind-bogglinly deep
formal argument:

	<http://www.w3.org/> dc:title "W3C".
	<http://www.w3.org/> dc:title "W3C".

That's it.*

"Duh!" you say. Indeed.

This is the "duh!" requirement: any formal
system in which formuala F doesn't entail
itself does not meet the "duh!" requirement.

TDL[TDL] does not meet the "duh!" requirement.
(the TDL proponents will please correct
me if I have misunderstood, but I'm pretty
sure, based on the clarification of TDL
I just got in the telcon, that it does not.)
Therefore I find it totally unacceptable.

All of the work that SWAD does on RDF
rules relies on the "duh!" requirement.

we write stuff like:

	:Fred :hairColor "red".

	{ ?x :hairColor "red" }
		log:implies { ?x a :RedHead }.

and we expect our system to conclude

	:Fred a :RedHead.

In the TDL proposal, I cannot do this,
because I am not licensed to infer
that the "red" in the first line and
the "red" in the head
of the rule denote the same thing
in all interpretations.

I'm pretty sure TDL undermines all
the other rules and query systems out
there (squish, RQL, etc.). I'm pretty
sure it undermines common use of
triplesMatching() APIs. All these
things assume that "abc" denotes
the same thing in all interpretations.

* If you don't like the argument on the
grounds that it's specific to n-triples,
please substitute this fully spelled-out
RDF 1.0 document as the premise and the conclusion:

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
<rdf:Description rdf:about="http://www.w3.org/">
<dc:title>World Wide Web Consortium</dc:title> </rdf:Description>

[TDL] Preview of working draft for TLD (PD) datatyping scheme proposal
From: Patrick Stickler (patrick.stickler@nokia.com)
Date: Wed, Jan 16 2002
-> http://www-nrc.nokia.com/sw/TDL.html

Note that I first made this argument in

Re: a test case for "literals must be self-evident"
From: Dan Connolly (connolly@w3.org)
Date: Mon, Dec 10 2001

I believe this argument is just an elaboration
of why Sergey finds "untidy literals" in
TDL graphs unacceptable.

Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Friday, 25 January 2002 11:27:28 UTC

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