Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.math

Topic: CON(ZF) and the ontology of ZF
Replies: 5   Last Post: Feb 19, 2013 3:53 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Charlie-Boo

Posts: 1,588
Registered: 2/27/06
Re: CON(ZF) and the ontology of ZF
Posted: Feb 18, 2013 12:11 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

On Feb 17, 1:53 pm, Zuhair <zaljo...@gmail.com> wrote:
> On Feb 17, 9:40 pm, fom <fomJ...@nyms.net> wrote:
>
>
>
>
>
>
>
>
>

> > On 2/17/2013 12:12 PM, Zuhair wrote:
>
> > > On Feb 17, 11:42 am, fom <fomJ...@nyms.net> wrote:
>
> > >> So, returning to the statements in the opening
> > >> paragraph, it does not surprise me that Zuhair
> > >> may have succeeded in devising a means by which
> > >> to show Con(ZF) relative to Morse-Kelley set theory.
> > >> Morse-Kelley set theory as presented in Kelley
> > >> presumes a global axiom of choice.

>
> > > The theory that I've presented can actually work without the axiom
> > > of global choice!

>
> > I believe this.  You represented the forcing methodology
> > directly.  And, I am now fairly convinced that that
> > methodology is implicit to the axiom of induction for
> > arithmetic.

>
> > Think carefully about how I ended that post.  I pointed
> > to a link explaining the relationship of AC to GCH

>
> > There is a reason I did that.  I do not ascribe
> > to the usual model theory for set theory.  It is not
> > logically secure.  Very few people like my posts,
> > but this is one attempt at explaining myself on
> > "truth" for set theory.

>
> > news://news.giganews.com:119/5bidnemPpsnq13zNnZ2dnUVZ_sOdn...@giganews.com
>
> > > this is done by replacing axiom of Universal limitation by
> > > axiom of direct size limitation.

>
> > > To re-iterate my theory. It is too simple actually.
>
> > > Language: FOL(=,e)
>
> > > Definition: Set(x) <-> Ey(x e y)
>
> > > Axioms:
>
> > > 1.Extensionality: (Az. z e x <-> z e y) -> x=y
> > > 2.Class comprehension: {x| Set(x) phi} exists.
> > > 3.Pairing: (Ay. y e x -> y=a or y=b) -> Set(x)
> > > 4.Hereditary limitation: Set(x) <-> Ey. Set(y) & AzeTC(x).z=<y
> > > 5.Size limitation: Set(x) & y=<x  -> Set(y)
> > > /

>
> > > where x =< y <-> Ef. f:x-->y & f is injective
> > > and TC(x)={y|As. x subset_of s & s is transitive -> y e s}

>
> > > This proves MK-choice. However it might be stronger than MK-choice?
> > > MK+global choice proves all the above axioms.

>
> > In general, I am unfamiliar with Morse-Kelley.  I have
> > read through the appendix of "General Topology", and
> > that does have only global choice.  So, I am not certain
> > of your distinctions here and cannot even begin to
> > address the question.

>
> There are many versions of MK, those differ by altering size
> limitation, for
> example this can be altered exactly as in this theory, so instead of
> Universal
> kind of size limitation (which is the usual in MK) we can use the one
> I wrote
> as the last of the axioms here, this will deprive MK from choice as it
> did here.
> Anyhow
>
> Zuhair


Zuhair,

Whenever someone says they can solve what seems to be a very difficult
problem, but never really describes exactly how it can be done because
of the complexity of it, I like to ask them: Ok, can you give a
detailed solution to a small representative subset of the problem to
illustrate your complete solution?

In this case, I would be interested in a detailed proof that any two
axioms are consistent, and a list of the other axioms you think are
also consistent with them. Of course the form of the two axioms would
have to be such that, on the surface they can be mutually
contradictory. For example, one could be of the form ?If xxx then yyy
is a set.? and the other of the form ?There is no set such that zzz.?

Can you show how you can prove even a simple subset consistent in
detail?

C-B



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.