Date: Mar 28, 2013 2:25 PM
Author: Zaljohar@gmail.com
Subject: Re: A reformulation of MK-Foundation-Choice: Even more compact!
On Mar 28, 2:07 pm, Zuhair <zaljo...@gmail.com> wrote:

> On Mar 23, 8:33 pm, Zuhair <zaljo...@gmail.com> wrote:

>

> > This is even more compact reformulation of MK-Foundation-Choice.

>

> > Unique Comprehension: if phi is a formula in which x is not free,

> > then:

> > (Exist x for all y (y in x iff set(y) & phi)) is an axiom.

>

> > Size limitation: Set({}) & [Set(x) & y =< H(TC(x)) -> Set(y)]

> > /

>

> It might be possible to further weaken that to the following

>

> Set({}) & [Set(x) & y=<H(x) -> Set(y)]

No this won't work we need H(TC(x)) as in the original formulation.

But for the sake of proving Con(ZC) yes we can use the weak axiom

Set({}) & [Set(x) & y =< H(x) -> Set(y)]

where =< is defined as:

y =< x iff Exist z (for all m. m in y & ~m in x -> m=z)

Zuhair

>

> I think this can interpret MK over the sub-domain of well founded

> sets, thus proving the consistency of ZFC relative to it.

>

> Also I do think that if we re-define =< to the following modified

> subset relation, then the resulting theory would prove the consistency

> of ZC relative to it.

>

> Def.) y =< x iff Exist z (for all m. m in y & ~m in x -> m=z)

>

> Zuhair

>