Re: A new proof of the superiority of set oriented approaches: numerical/time serie linear interpolation


"Cimode" <cimode@xxxxxxxxxxx> wrote in message
news:1177938789.949723.62480@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
[snip]
I am aware of that article but thank you for reminding it. It simply
a negation of previous work and has been demonstrated since as wrong
by Codd's disciples (Date, Darwen). The induction of NULL 3VL simply
breaks the POCW (Principle of Closed World) redefining the meaning of
a database as a collection of facts. I think of this tolerance as one
of Codd's errors.


In a closed world, there is no such thing as "missing information." Can you
provide a reference that states that Codd adopted the closed world
assumption? I've never read that he did, and in light of his views on
missing information, I would be surprised if he had. In an open world, the
focus is on what has been stated, and the contents of a database is a
collection of recorded facts, not a collection of all of the facts. D&D's
interpretation of the RM differs from Codd's in several substantive ways.
Aside from missing information, Codd never described a database as a
collection of relvars. In everything I've read, he has always referred to
database modifications as inserts, updates and deletes. This would follow,
since inserts, updates and deletes are statements that specify how what is
known about the universe now differs from what has already been recorded.
D&D's interpretation posits that insert, update and delete are simply
instances of relational assignment, blissfully ignoring their inherent
dependency on the current state.


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