Prove that P(N) is equipotent with the set of functions 2N = {f : N → {0, 1} : f is a function}. In particular, the cardinality of P(N) is 2ℵ

Elements Of Modern Algebra
8th Edition
ISBN:9781285463230
Author:Gilbert, Linda, Jimmie
Publisher:Gilbert, Linda, Jimmie
Chapter1: Fundamentals
Section1.5: Permutations And Inverses
Problem 6E: 6. Prove that if is a permutation on , then is a permutation on .
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Prove that P(N) is equipotent with the set of functions

2N = {f : N → {0, 1} : f is a function}.

In particular, the cardinality of P(N) is 20

Expert Solution
Step 1

Given that,

f:N{0,1}:f is a function 

The aim is to show that, P(N)=f:N{0,1}:f is a function

The infinite sequences of 0s and 1s can be stated as a result about the power set of N, P(N).

An infinite sequence is a function f : N → {0, 1}

And the set of such sequences is usually denoted 0,1N.

A subset A ⊂ N defines a function f : N → {0, 1}:

f(n)=1 if nAand f(n)=0 if nA.

 

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