Exercise 1. Let S(N) be the set of strictly increasing functions ƒ : N → N; ie. those functions of such that f(n) < f(m) for all 0 ≤ n < m. Prove that S(N) ≈ P(N). Exercise 2. A function f : N N is said to be a quasi-identity function if |f(n) - n ≤ 1 for all n = N. Determine whether the set QI(N) of quasi-identity functions is countable or uncountable. Exercise 3. Prove that if Sym(N) is the set of bijections : N → N, then card(Sym(N)) = 2. (Hint: consider the bijections : N → N such that [{ 2n, 2n+1}] = {2n, 2n+1} for all nЄ N.)

College Algebra (MindTap Course List)
12th Edition
ISBN:9781305652231
Author:R. David Gustafson, Jeff Hughes
Publisher:R. David Gustafson, Jeff Hughes
Chapter3: Functions
Section3.3: More On Functions; Piecewise-defined Functions
Problem 99E: Determine if the statemment is true or false. If the statement is false, then correct it and make it...
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Exercise 1. Let S(N) be the set of strictly increasing functions ƒ : N → N;
ie. those functions of such that f(n) < f(m) for all 0 ≤ n < m.
Prove that S(N) ≈ P(N).
Exercise 2. A function f : N N is said to be a quasi-identity function if
|f(n) - n ≤ 1
for all n = N.
Determine whether the set QI(N) of quasi-identity functions is countable or
uncountable.
Exercise 3. Prove that if Sym(N) is the set of bijections : N → N,
then card(Sym(N)) = 2.
(Hint: consider the bijections : N → N such that [{ 2n, 2n+1}] = {2n, 2n+1}
for all nЄ N.)
Transcribed Image Text:Exercise 1. Let S(N) be the set of strictly increasing functions ƒ : N → N; ie. those functions of such that f(n) < f(m) for all 0 ≤ n < m. Prove that S(N) ≈ P(N). Exercise 2. A function f : N N is said to be a quasi-identity function if |f(n) - n ≤ 1 for all n = N. Determine whether the set QI(N) of quasi-identity functions is countable or uncountable. Exercise 3. Prove that if Sym(N) is the set of bijections : N → N, then card(Sym(N)) = 2. (Hint: consider the bijections : N → N such that [{ 2n, 2n+1}] = {2n, 2n+1} for all nЄ N.)
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