Corollary. Every infinite set contains a proper subset to which it is similar. Proof. Let A be an infinite set and let S = {a, az, ..} be a count- ably infinite subset of A. The function f: A → A-{a;} defined by (an+1 if x = a, (n = 1, 2, ...), if x € A-S %3D f(x) = (x is a bijection. Thus A ~ A-{a,}. |

Algebra: Structure And Method, Book 1
(REV)00th Edition
ISBN:9780395977224
Author:Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. Cole
Publisher:Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. Cole
Chapter2: Working With Real Numbers
Section2.1: Basic Assumptions
Problem 40WE
icon
Related questions
Question

Show in detail that is a bijection (Corollary's proof)

ove that every infinite set S contains a proper subset similar to S
Clear search
Theorem 1.42. Every infinite set contains a countably infinite subset.
Proof. Let A be an infinite set. Take some element of A and call
it az. The set A-{az} is not empty; denote one of its elements by az.
This process may be continued indefinitely: at the nth stage the set
A-{a1, ..., an-1}
cannot be empty since A is infinite. The set {a,, a„ ..} is a countably
infinite subset of A. ||
Corollary. Every infinite set contains a proper subset to which it is
similar.
Proof. Let A be an infinite set and let S = {a, az, ..} be a count-
ably infinite subset of A. The function f: A → A-{az} defined by
%3D
(an+1 if x = a, (n = 1, 2, ..),
f(x)
if x e A-S
is a bijection. Thus A ~ A-{az}. |
Transcribed Image Text:ove that every infinite set S contains a proper subset similar to S Clear search Theorem 1.42. Every infinite set contains a countably infinite subset. Proof. Let A be an infinite set. Take some element of A and call it az. The set A-{az} is not empty; denote one of its elements by az. This process may be continued indefinitely: at the nth stage the set A-{a1, ..., an-1} cannot be empty since A is infinite. The set {a,, a„ ..} is a countably infinite subset of A. || Corollary. Every infinite set contains a proper subset to which it is similar. Proof. Let A be an infinite set and let S = {a, az, ..} be a count- ably infinite subset of A. The function f: A → A-{az} defined by %3D (an+1 if x = a, (n = 1, 2, ..), f(x) if x e A-S is a bijection. Thus A ~ A-{az}. |
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 3 steps with 1 images

Blurred answer
Recommended textbooks for you
Algebra: Structure And Method, Book 1
Algebra: Structure And Method, Book 1
Algebra
ISBN:
9780395977224
Author:
Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. Cole
Publisher:
McDougal Littell
Elements Of Modern Algebra
Elements Of Modern Algebra
Algebra
ISBN:
9781285463230
Author:
Gilbert, Linda, Jimmie
Publisher:
Cengage Learning,
College Algebra
College Algebra
Algebra
ISBN:
9781938168383
Author:
Jay Abramson
Publisher:
OpenStax
College Algebra
College Algebra
Algebra
ISBN:
9781305115545
Author:
James Stewart, Lothar Redlin, Saleem Watson
Publisher:
Cengage Learning
Elementary Linear Algebra (MindTap Course List)
Elementary Linear Algebra (MindTap Course List)
Algebra
ISBN:
9781305658004
Author:
Ron Larson
Publisher:
Cengage Learning