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Topic: Uncountability of the Real Numbers Without Decimals
Replies: 110   Last Post: Dec 10, 2013 4:33 AM

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Tucsondrew@me.com

Posts: 783
Registered: 5/24/13
Uncountability of the Real Numbers Without Decimals
Posted: Dec 2, 2013 3:09 AM
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The following is a Proof of the Uncountability of the Set of real Numbers. Please note that it avoids the use the Representation of the Real Numbers as Infinite Decimals. It uses only the Property of Completeness (that every Set of Real Numbers that is bounded above has a Least Upper Bound which is a Real Number); and some Properties due to the Ordering of the Real Numbers, such as if x is Real Number then there exist Real Numbers a and b such that a < b and x ~e [ a, b ].

The proof proceeds by Contradiction. We assume the Set of Real Numbers is Countable, and thus can be exhausted in a Sequence.

Take any such Sequence of Real Numbers, X = { x_n | n e N }. We begin by choosing Real Numbers, a_1 and b_1, such that a_1 < b_1 and x_1 ~e [ a_1, b_1 ]. Next, we choose Real Numbers, a_2 and b_2, such that a_1 < a_2 < b_2 < b_1 and x_2 ~e [ a_2, b_2 ]. We continue by choosing Real Numbers a_k and b_k for every k e N, such that for every k e N, we have
a_k-1 < a_k < b_k < b_k-1 and, of course, x_k ~e [ a_k, b_k ].

Doing so for every Natural Number, we define A = { a_n | n e N }. Now, A is a Set of Real Numbers that is bounded above, since any b_n is an upper bound of A. Hence, a = sup(A) is a Real Number. Since our Sequence, X, exhausts all Real Numbers, a e X and there is a Natural Number, m, such that x_m = a.

Now, we have previously defined Real Numbers, a_m and b_m, such that a = x_m ~e [ a_m, b_m ]. However, we know a_m <= a, since a = sup(A) and a e A; and a <= b_m, since any b_n is an upper bound of A. These together give us that we must have x_m e [ a_m, b_m ]. This results in a Contradiction. Hence, we must have that the Set of Real Numbers is Uncountable.

qed

I find the proof rather straight forward. Question, comments, suggestions and corrections are welcome.

ZG


Date Subject Author
12/2/13
Read Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
William Elliot
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
G. A. Edgar
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
gnasher729
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/10/13
Read Re: Uncountability of the Real Numbers Without Decimals
Robin Chapman
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Michael F. Stemper
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/6/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/6/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/6/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/6/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/6/13
Read Re: Uncountability of the Real Numbers Without Decimals
Brian Q. Hutchings
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
Brian Q. Hutchings
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
Brian Q. Hutchings
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
fom
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
albrecht
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
fom
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
ross.finlayson@gmail.com
12/8/13
Read Re: Uncountability of the Real Numbers Without Decimals
albrecht
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
fom
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
fom
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
fom
12/8/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/8/13
Read Re: Uncountability of the Real Numbers Without Decimals
albrecht
12/6/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/6/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Michael F. Stemper
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
fom
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/2/13
Read Re: Uncountability of the Real Numbers
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers
wolfgang.mueckenheim@hs-augsburg.de
12/3/13
Read Re: Uncountability of the Real Numbers
Virgil
12/5/13
Read Re: Uncountability of the Real Numbers
wolfgang.mueckenheim@hs-augsburg.de
12/5/13
Read Re: Uncountability of the Real Numbers
Virgil
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
gnasher729
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
gnasher729
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
gnasher729
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/7/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/8/13
Read Re: Uncountability of the Real Numbers Without Decimals
wolfgang.mueckenheim@hs-augsburg.de
12/8/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Virgil
12/2/13
Read Re: Uncountability of the Real Numbers Without Decimals
ross.finlayson@gmail.com
12/4/13
Read Re: Uncountability of the Real Numbers Without Decimals
ross.finlayson@gmail.com
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
albrecht
12/3/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
albrecht
12/5/13
Read Re: Uncountability of the Real Numbers Without Decimals
Tucsondrew@me.com

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