Re: E/R modeling: relationship's attributes
Date: Thu, 04 May 2006 16:30:32 GMT
Message-ID: <I_p6g.123513$WI1.107827_at_pd7tw2no>
Mikito Harakiri wrote:
> U-gene wrote:
>
>>... it tryes to describe some enterprise, its >>entitites, relationships ets, what exist in real world ...
>
>
> Do you understand the difference between the model and the real world?
>
> (Prof Krasnoselsky used to puzzle his students with a linear control
> system that was supposed to output the input signal shifted forth in
> time -- predict the future in other words. After a humble student's
> attempt to explain that such system would be unstable prof asked such
> question. I interpret it as a retorical question that ends the
> discussion.)
>
Could have been Prof. Raskelnikov for all I know, just kidding. It's certainly a rhetorical question and a darned good one IYAM. William Kent, widely-quoted practioner and writer (died recently, not exactly Codd's generation in years, but certainly the same DP generation) wrote this in the preface to his neat little book, "Data and Reality":
"Along the way, we implicitly suggest a hypothesis (by sheer weight of examples, rather than any kind of proof -- such a hypothesis is beyond proof): there is probably no adequate formal modelling system. Information in its "real" essence is probably too amorphous, too ambiguous, too subjective, too slippery and elusive, to ever be pinned down precisely by the objective and deterministic processes embodied in a computer."
more excerpts at: http://www.bkent.net/Doc/darxrp.htm
It might be interesting if the OO/MV people would reference Kent's examples so that the rest of us could know exactly which one they're talking about at any particular time!
p Received on Thu May 04 2006 - 18:30:32 CEST