Re: Reflections of a beautiful mind... Fundamental principle: Separation of Concerns

From: Frank Hamersley <>
Date: Mon, 24 Apr 2006 04:47:33 GMT
Message-ID: <FLY2g.14250$>

Bob Badour wrote:
> Returning to comp.databases.theory and the discussions here has prompted
> me to delve into the EWD archive at utexas. Like an inexhaustible jewel
> mine, the archive is full of great riches: gems reflecting a beautiful
> mind.

Yes - always a humbling experience for me at least!

> For instance, re-reading EWD 709:
> I stumble across this gem:
> "How well are we, for instance, able to separate the concern for
> correctness from the concern for efficiency? Both concerns are so
> "major", that I don't believe that significant progress will be possible
> unless we manage to separate them completely."
> I often speak of physical independence as a principle; however, the real
> principle is the separation of concerns, of which physical independence
> is just one example as so eloquently stated by EWD above.
> Similarly, logical independence separates the concern for correctness
> from the concern for convenience.
> EWD lists three fundamental principles:
> 1) separation of concerns and effective use of abstraction
> 2) the design and use of notations, tailored to one's manipulative needs
> 3) avoiding case analyses, in particular combinatorially exploding ones.
> I wonder how many other principles distill down to just these three?
> For instance, the third principle would seem to argue strongly against
> null and n-vl.

But isn't that the very technique (combinatorial explosion) that D+D propose with D?

Cheers, Frank. Received on Mon Apr 24 2006 - 06:47:33 CEST

Original text of this message