Re: Proposal: 6NF
Date: 8 Oct 2006 11:08:28 -0700
Message-ID: <1160330908.392941.214900_at_i3g2000cwc.googlegroups.com>
dawn wrote:
> OK, Cimode -- What is your definition of "function"? Is there some
> > > > You did not demonstrate anything except that you don't understand
> > http://en.wikipedia.org/wiki/Function_(mathematics)
> Are you thinking that functions that do not
> 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.
> > 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
> > //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....
> 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...
> 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...
Received on Sun Oct 08 2006 - 20:08:28 CEST