Re: theory and practice: ying and yang
Date: Sun, 29 May 2005 11:06:18 GMT
Message-ID: <Kmhme.6076$BR4.5780_at_news-server.bigpond.net.au>
"Paul" <paul_at_test.com> wrote in message
news:42986b62$0$93748$ed2619ec_at_ptn-nntp-reader01.plus.net...
> mountain man wrote:
>>>>Date ignores the proofs of Godel and Chaitin.
>>>
>>>This is plain nonsensical.
http://www.mountainman.com.au/software/history/relational_model_incomplete.htm
- ALSO ***
>> Codd, not Date, was the author of the RM.
>> Codd reserves a place for nulls.
>> Date does not.
>> End of story.
>
> How are nulls related to Godel and Chaitin?
They are not (necessarily) related, it is simply an additional statement of an issue: that Codd and Date differred in opinion on the treatment of nulls by the theory (RM).
> Although Godel's theorems are named "undecidability" and
> "incompleteness", I think this is in a totally different way to the
> question of the use of nulls.
>
> It seems to me that the null issue is all about whether unknown values
> should be handled by the relational engine (as in SQL, using 3-valued
> logic) or in the type engine, i.e. set up specifically for each
> domain/type.
You are correct above on both counts.
They are not (necessarily) related.
Sorry for any confusion.
-- Pete Brown IT Managers & Engineers Falls Creek Australia www.mountainman.com.au/usenet.htmlReceived on Sun May 29 2005 - 13:06:18 CEST