Re: Proposal: 6NF
Date: 8 Oct 2006 14:18:42 -0700
Message-ID: <1160342322.202948.263130_at_i3g2000cwc.googlegroups.com>
Cimode wrote:
> Marshall wrote:
> [Snipped]
>
> It seems quite clear that debate is about SQL NULLS
The original discussion was about SQL NULLS. This is a theory group, however, so when discussing where we think the theory should go, it need not bring SQL along with it. There are many places where NULLS (in computer languages & data management tools) are not handled the same as SQL NULLS.
> and the miserable
> treatment of missing data they represent...One thing leading to
> another, some idiots still believe that a SQL NULLS represent a value
You were able to understand that at every turn I indicated that I was not talking about SQL NULLS, right? They do not represent values, even though other NULLS do. There is nothing about database theory or even relational theory that requires NULLS not to be values. There are examples of relations with NULL values addressed in DBMS's. This is not the case with SQL, however, where I think everyone is in agreement that NULL does not represent a value.
> while it was demonstrated to them that it does not fit the classical
> definition of a value being the output of a predetermined algebric
> function..
I think we were talking about functions in general. I understand where you might not understand my definition of NULL (if your experience were primarily SQL, for example), Marshall did not help in clarifying what in the world your definition of a function might be. You just added in two adjectives to "function", perhaps in an attempt to give me clues what you are trying to say when you suggest the functions I proposed are not functions. If you could be explicit in you definition of "function" that would still be helpful. If you are otherwise willing to state that you understand now that you did not understand functions, then there is no need to tell me your definition.
>.To make a case, people like dawn are willing to set up their
> own definition of mathematical functions
I did not write my own definition. I'm working with the one that is in the cdt glossary that came from standard mathematics.
[Function]
Math
A binary mathematical relation with at most
one b for each a in (a,b).
[Relation]
1. A relation is a subset of the set of ordered tuples (A1, A2, ... Am) formed by the Cartesian cross-product of sets S1 x ... x Sm where each An is an element of Sn.
What we are missing is your definition of "function."
> to try to prove
> anything...They are confused and confusers...What a shame she teaches
> such bulshit to her student...
Then you will be pleased to know that I rarely teach (5 years in my almost 30 year career)
Cimode -- we can certainly write each other off, but I also think that we could put our definitions on the table and try to understand what the other means by their statements. What is your definition of a function and why do the functions that I presented not qualify as functions by your definitions? Is it because of a flawed definition you have of "function" or because you are talking about an SQL NULL, which I think I have repeatedly said is not the NULL value I am talking about? I would rather that we each understood the other before simply dropping it, if you are willing to put your cards (definitions) on the table.
Thanks. --dawn Received on Sun Oct 08 2006 - 23:18:42 CEST