Re: Proposal: 6NF

From: dawn <dawnwolthuis_at_gmail.com>
Date: 8 Oct 2006 11:22:11 -0700
Message-ID: <1160331731.102330.36090_at_m7g2000cwm.googlegroups.com>


Cimode wrote:
> dawn wrote:
>
> > OK, Cimode -- What is your definition of "function"? Is there some
> > resource on the web that defines "function" your way? I'm using what I
> > know to be a valid mathematical definition of a function. I believe it
> > also aligns with one in the cdt glossary. We are going to go around in
> > circles if you have a definition of a function that differs with this.
>
> > > > > You did not demonstrate anything except that you don't understand
> > > the
> > > > > formal mathematical definition of a function...
> > > >
> > > > If someone will confirm that you are correct in this, I will revisit
> > > > what I have though to be the definition of a function. I suspect,
> > > > however, that you are the one who needs to revisit the definition and
> > > > verify that I have presented you now with two functions where NULL is a
> > > > value in the range of the function.
> > > What you have presented is NOT a mathematical function
>
> > > http://en.wikipedia.org/wiki/Function_(mathematics)
> > > //In mathematics, a function relates each of its inputs to exactly one
> > > output. A standard notation for the output of the function f with the
> > > input x is f(x). The set of all inputs that a function accepts is
> > > called the domain of the function.//
> >
> > OK, so you do have an acceptable description of a function, so what are
> > you not understanding?
> Hear , Hear I am not understanding now....
>
> > Are you thinking that functions that do not
> > have the domain and codomain (set from which the range values come) as
> > the set of real numbers are not functions? My first function can be
> > represented as f(x) where x is an element of {"M","F",NULL} while the
> > second can be represented as f(x) where x is an element of the interval
> > [0,1]. I could produce one whose domain is all real numbers if that
> > would suit your fancy, but the domain would not be all real numbers,
> > because you were looking for a function where the output could be NULL.
> > NULL is represented mathematically as {} (not in SQL, of course,
> > where it is not a value, but an indicator for the lack of a value}.
> Why are you bringining codomain intot that? You can not define a value
> and you try to deal with codomain...
> It is obvious to me now that you have no clue of what a function
> is...Let's stop the debate..You are a lost cause...
>
> > So, I think you need to understand sets that are not simply from and to
> > the real numbers. This is not intended to be a jab, but you really
> > could start with the exercises we give pre-schoolers where there is a
> > set of animals they then map to the sounds they make, or a set of hats
> > which map to people in professions who wear those hats. Get back to
> > the definition of a function so that you really grok it, then see if
> > you understand what I am writing. Each element in the domain of the
> > function maps to one and only one element in the codomain.
> Let set this clear...
> A value is defined the output of ANY function and can be of ANY
> domain...You do not describe function through single values but through
> a valid algebric definition...Which you failed to do on ALL
> occasions...Again it seems obvious you have no clue of what a function
> is.
>
> > Many developers work with a data/language combination where a NULL
> > value is treated mathematically as the empty set.
> If they do it the same way you do math, I doubt any relevance in any of
> what they do...Thanks god I know all programmers are not as ignorant as
> that
>
> > > > > You consider as logical
> > > > > *proof* a specific example of implementation (open source bulshit)...
> > > >
> > > > Nope, that was not the logical proof -- the function was. In case you
> > > > were confused, I suggested you could give it a whirl in an open source
> > > > dbms.
> > > That is not a god damn function...A function is not defined throught
> > > intervals...
> >
> > Again, you must have such a different perspective of what a function is
> > than what I have learned (and taught) that we will get no where until
> > you a) provide your definition and preferably also b) you learn the
> > standard mathematical definition.
> Definition provided was clear enough...Only algebra defines and
> expresses functions..The rest is just crap...If you taught this to your
> students that says a lot about the poor level of math in the US...
>
> > > [nonsense snipped]
> > >
> > > > Sometimes confused, but in this case not so much. smiles. --dawn
> > > Only idiots smile at their ignorance...
> >
> > Or completely misread the smiles of others? --dawn
> Yeah whatever...In any case, I have wasted enough time exchanging with
> you...So good luck with your functions (for whatever they may be)..Go
> try play math with ignorants...

I gave you a chance, Cimode, to give a clear definition of a function which would exclude my examples as being functions. You did not do so.  I tried to guess what you might be misunderstanding in either what I wrote or related to the definition of a function, but based on your responses, I simply cannot guess what you think a function to be. If anyone else could jump in and give me a clue what they think Cimode thinks to be a function, I am curious. The fact remains that a NULL value (not an SQL NULL) may be in either the domain or range of a legitimate function. --dawn Received on Sun Oct 08 2006 - 20:22:11 CEST

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