The Math Forum

Search All of the Math Forum:

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

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

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Simple analytical properties of n/d
Replies: 20   Last Post: Mar 11, 2013 11:01 PM

Advanced Search

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

Posts: 2,720
Registered: 2/15/09
Re: Simple analytical properties of n/d
Posted: Mar 9, 2013 3:55 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

On Mar 8, 9:31 pm, William Elliot <> wrote:
> On Fri, 8 Mar 2013, Ross A. Finlayson wrote:
> > Putting aside these remarkable features of n/d, as evaluated in the
> > limit, twice, that the resulting triangle with two-sided points has
> > exactly unit area, there is plenty to consider with regards to ran(f)
> > for f: N -> R_[0,1].

> What's R_[0,1]?  So now your considering any function f:N -> [0,1]
> and want to discuss rang f.

> > Obviously and directly as N is countable, were ZF consistent and R a
> > set in ZF, vis-a-vis its having an arbitrarily large cardinal, ran(f)
> > is countable, in as to whether ran(f) = R_[0,1].  Here, to say that
> > ran(f) = R_[0,1], has that it would be sufficient to represent each
> > real in R_[0,1], in particular systems of analytical interest,
> > compared to:  that it IS R_[0,1], with a concomitant following
> > construction of R for its use as the complete ordered field (unique,
> > up to isomorphism, in infinite ordered fields).

> Gibberish except for the observation that range f is countable.
> This means that your statement range f = [0,1] is false.

> > Then, this is about detailing the analytical properties of n/d, with
> > the natural integers defined, (or as above as a natural continuum of
> > natural integers):  before the properties of rings, fields, and the
> > ordered fields and the complete ordered field are defined.  Monoids in
> > algebra are formal structures, but they are built upon a more
> > primitive and here the primeval structure of the continuum, first as
> > distinct integers then to the divisions and partitions of one integer,
> > the unit, then via extensions among each, all in the positive
> > (Bourbaki), and only then to the ring of integers, fields of fractions
> > and rationals and reals, and at once:  ring of reals.

> I'll skip this as you set aside n/d.

> > Then for ran(f) being f: N -> ran(f), and that having structural
> > qualities for use as a building block of then higher level algebraic
> > structures, a variety of results unavailable to the standard, are
> > formalizable.

> Huh?  Is that the output of Ross' random thought generator in math mode?

> > Is ran(f) = [0,1]?  Is ran(g) for g = x for x from 0 to 1, [0,1]?  Are
> > all the ranges of functions with image [0,1] equal to [0,1]?  Then,
> > [0,1] isn't just the points in a set, it's all of those.  In as to
> > types, then, there's a notion that:  ran(f) = [0,1].

> Of course not, you showed that range f is countable and
> unable to be any uncountable set.

Apply the antidiagonal argument to ran(f).
the only item different from each is
and, ran(f) includes 1.0.

Apply the nested intervals argument to ran(f).
The interval is [.0, .1], there's no missing element from ran(f)'s

The antidiagonal argument and nested intervals argument don't support
that ran(f) =/= [0,1].

In fact, remarkable among functions N -> R, is that the antidiagonal
argument and nested intervals argument, DON'T apply to f.


Ross Finlayson

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

[Privacy Policy] [Terms of Use]

© The Math Forum at NCTM 1994-2018. All Rights Reserved.