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Re: Data models as constraints

From: Hassan At-Kaci <hak@ilog.com>
Date: Tue, 16 Jan 2007 16:45:59 +0100
Message-ID: <45ACF337.3070800@ilog.com>
To: Gerd Wagner <wagnerg@tu-cottbus.de>
CC: W3C RIF WG <public-rif-wg@w3.org>

Gerd Wagner wrote:

>>I have finalized the writeup on data models as constraints. 
>>It is available as
>>Comments are welcome.
> Hassan, it seems that you have completely ignored the 
> fundamental issue of negation-as-failure (NaF), also 
> called "negation-by-default", and the related issue 
> of open vs. closed predicates in your paper. 
> Why? Because you didn't consider that (yet) in your 
> OSF formalism?

Hi Gerd,

Thanks for your comment on my paper: you must be the fastest reader
that I have come across in my life! ;-)

Re. your comment, I must say thay I do not quite understand what it
has to do with either the topic of the article, nor  what it means.
What I wrote about is simple: because CLP makes rules and constraints
orthogonal, it offers a way to use rules over arbitrary data models
- not just data and FOTs. I then focused on the OSF and DL formalisms
seen as constraint systems for objects and inheritance. The nature of
the rules is *not* important and may be of all kinds including Horn,
(with or without negations or all kinds), Production, YouNameIt, ...

> How can you capture SQL, Prolog and production rules
> without supporting NaF?

Again the focus of my paper is *NOT* on the rules but (as the title
states it clearly) about *data models as constraint systems*.

Also, the nature of the paper is that of a (semi-formal) tutorial
- not an exhaustive survey about all known or possible ways to
conjugate rules and data. Perhaps you should write such an article?

This notwithstanding, the way negation is handled for OSF terms (see
Section 3.1.5) implicitly uses a CWA on the set of sort. I admit that
I should make this fact clear.

Finally, this is just a journal article, not a book! Isn't a 40-page
paper, in 10pt font fullpage layout, long enough for you?  :-)

At any rate, I am sorry that you find my work of debatable interest
for your needs, and I apologize for disappointing your expectations.

Be that a it may, thanks again for caring to give me some feedback
with your comments.

> -Gerd


Hassan At-Kaci
ILOG, Inc. - Product Division R&D
tel/fax: +1 (604) 930-5603 - email: hak @ ilog . com
Received on Tuesday, 16 January 2007 15:46:58 UTC

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