Re: infinity
- From: Tony Orlow <aeo6@xxxxxxxxxxx>
- Date: Tue, 4 Oct 2005 12:06:55 -0400
David R Tribble said:
> Matt Gutting said:
> >> I recall you defining the "value range" of a set as the maximum difference
> >> between any two elements of the set. Without regard to whether this
> >> difference is finite or infinite, bounded or unbounded, can you demonstrate
> >> that such a difference exists for any arbitrary set (of natural numbers)?
> >
>
> Tony Orlow wrote:
> > Think of it as the largest POSSIBLE difference in the set. There is no
> > possible infinite difference between finite values. The largest possible
> > difference between finites is finite. Any set of values has some range,
> > some set of differences.
>
> And yet you stated elsewhere in this thread that the maximum range of
> the real points in S = (0,1] was 1, even though the difference between
> any two finite points in S is always less than 1.
And then emended it to say that the range of such an open set is "<1", which
would mean arbitrarily close to but less than 1. The range of the finite
naturals is "<oo".
>
> Quote:
>
> Randy Poe said:
> >> But there is no pair of values separated by 1
> >> [in the set of reciprocals of finite positive naturals],
> >> so this contradicts your own definition of range.
> >
>
> Tony Orlow wrote:
> > Maximum POSSIBLE difference between values in the set. If there are
> > an infinite number of elements int he set, then you will have
> > elements infinitely close to 1, which standard math would consider
> > equal to 1.
>
> So you seem to be willing to grant that a set of reals can have a range
> greater than any possible difference between any two of its members,
> but that a set of naturals can't.
>
> Why is that?
It really can't. That was the first time I was asked about such an interval,
and it wasn't well thought out, since I had been thinking in terms of the
naturals. An open interval' range can be expressed using a "<" to denote the
lack of maximal element. I'd also say that (0,1), [0,1) and (0,1] all have the
same range of <1.
>
>
--
Smiles,
Tony
.
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