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Topic: Paraphrasing MK
Replies: 1   Last Post: Nov 21, 2012 10:34 AM

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Posts: 822
Registered: 9/1/10
Re: Paraphrasing MK
Posted: Nov 21, 2012 10:34 AM
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On Nov 21, 12:31 am, Zuhair <> wrote:
> Another way to present MK (which of course prove the consistency of
> ZF) is the following:
> Language: FOL(=,e)
> Define: set(x) <-> Exist y. x e y
> Axioms: ID axioms +
> (1) Unique Construction: if P is a formula in which y occur free but x
> do not, then
> all closures of (Exist! x. for all y. y e x <-> set(y) & P) are
> axioms.
> (2) Size: Accessible(x) -> set P and NP(1) respectively [MIN. c, ch, K]. In particular(.) the NP complete(?ch) languages have been studied intensively and virtually hundreds of natural NP complete (replete) problems have been found in many different areas oMus@ov(x)
> Where Accessible(x) is defined as:
> Accessible(x) <-> (Exist maximally two m. m e x) OR
> ~ Exist y:
> y subset of x &
> y is uncountable &
> y is a limit cardinal &
> y is not reachable by union.
> Def.) y is a limit cardinal <-> (for all y. y<x -> Exist z. y<z< x)
> Def.) y is reachable by union <-> (Exist y. y < x & x =< U(y))
> The relation < is "strict subnumerousity" defined in the usual manner.
> The relation =< is subnumerousity defined in the usual manner.
> "subset of" and "uncountable" also defined in the usual manner.
> "Exist maximally two m. phi(m)" is defined as
>  Exist m,n for all y. phi(y) -> y=m or y=n
> U(y) is the class union of y, defined in the customary manner.
> /
> So simply MK is about unique construction of accessible sets, and
> proper classes of those.
> Zuhair

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