On Apr 16, 10:39 am, Graham Cooper <
grahamcoop...@gmail.com> wrote:
> 1. Naive Set Theory
>
> y = { x | P(x) }
>
> _______________________________
>
> 2. Zermelo Frankel Set Theory (ZFC)
>
> ZFC Axiom Of Specification
> A(z): A(p1,p2..pn):
> E(y): A(x): x e y <-> (x e z & P(x,y,p1,p2..pn))
>
> MORE SIMPLY
> y = { x | x e z & P(x,y) }
>
If we let NAIVE SET THEORY set instances be defined via some predicate
P
E(Y) X e Y <-> P(X,Y)
THEN ZFC is merely the weaker formula
E(Y) X e Y -> P(X,Y)
********************
We us an Implication for ZFC
instead of a BiConditional for Naive S.T.
That's the only difference!
PROOF:
GIVEN:
Y C Z
<->
X e Y -> X e Z
GIVEN:
E(Y) X e Y -> P(X,Y)
THEN:
X e Y -> (X e Z) & P(X,Y)
GIVEN:
A(x,y)
y = { x | x e Y }
THEN
y = { x | x e z & P(x,y) }
QED
ZFC is derived from one side of the implication of NAIVE SET THEORY
****************
NAIVE SET THEORY
E(Y) X e Y <-> P(X,Y)
ZFC
E(Y) X e Y -> P(X,Y)
Basically a formula to define SUBSETS! Pairing and what not were
tacked on to compensate for this weakness and the whole "constructable
Universe" was invented thereafter!
Herc