Re: Pizza Example

In message <z1dic.11395$lu5.116_at_newssvr31.news.prodigy.com>, Eric Kaun <ekaun_at_yahoo.com> writes
>"Anthony W. Youngman" <wol_at_thewolery.demon.co.uk> wrote in message
>news:p6Md1aE8iwhAFw09_at_thewolery.demon.co.uk...
>> I've actually managed to work out a formal statement of what I always
>> suspected.
>>
>> "Normalisation by non-loss decomposition" is impossible. The law of
>> entropy says so.
>
>Does entropy apply to information?

Well, seeing as entropists refer to information as the opposite of entropy, I would guess it does :-)
>
>> So, to rephrase your last sentence, "By extracting the data from the
>> real world and storing it in ANY database you are changing it in some
>> sense, and losing data IS INEVITABLE."
>
>This is true.
>
>> The more you change it, the more you lose.
>
>This is not. Or at least, you also gain. And I'd distinguish potential
>information ("raw data"?) from information structures. I don't prefer to
>have my system encode every bit of verbiage spouted by a potential user in
>requirements-gathering.

Gain what? The analysis has to pour (different) data in to replace the data that's been lost.

And anyway, a relational transform turns structure into data, which bites you when ...
>
>> And the more you decompose
>> it, the closer you get to the point where "cause and effect" ceases to
>> have meaning :-) (which means it gets more and more likely, that an
>> attempt to get back to where you started will leave you somewhere else
>> entirely :-)
>
>That assumes you need to get back to where you started, which isn't a goal I
>necessarily have in mind. If I do, it's called a text document. My goal is
>not to reassemble a paper purchase order from data in a database - I usually
>need to present different views of the data, and do something interesting
>other than regurgitating it to the user verbatim.
>
When you need to regurgitate what was on a particular purchase order.

Especially if the analyst forgot the data was a list not a set :-)

Cheers,
Wol

-- 
Anthony W. Youngman - wol at thewolery dot demon dot co dot uk
HEX wondered how much he should tell the Wizards. He felt it would not be a
good idea to burden them with too much input. Hex always thought of his reports
as Lies-to-People.
The Science of Discworld : (c) Terry Pratchett 1999