Consider the function by , where is the ceiling function ( , , , ,... )
That is if n is odd and if n is even. Therefore we can restate the function as. Clearly f is a well defined function (unique image for every natural numbers) every element in C has unique pre-image. Hence f is a bijection between and C and thus C is countable.
9. Show that the set C N × a, b is countable by constructing a bijection...
Let S be a finite set with cardinality n>0. a. Prove, by constructing a bijection, that the number of subsets of S of size k is equal to the number of subsets of size n- k. Be sure to prove that vour mapping is both injective and surjective. b. Prove, by constructing a bijection, that the number of odd-cardinality subsets of S is equal to the number of even-cardinality subsets of S. Be sure to prove that your mapping is...
3. (8 marks) Let be the set of integers that are not divisible by 3. Prove that is a countable set by finding a bijection between the set and the set of integers , which we know is countable from class. (You need to prove that your function is a bijection.) We were unable to transcribe this imageWe were unable to transcribe this imageWe were unable to transcribe this imageWe were unable to transcribe this image
2. Determine whether the given sets are countable or uncountable. Justify each answer with a bijection (or table like we did with Q+) or using results from class/textbook. (a) {0, 1, 2} * N (b) A = {(x, y) : x2 + y2 = 1} (c) {0, 1} R Che set of all 2-element subsets of N (e) Real numbers with decimal representations consists of all 1s. (f) The set of all functions from {0,1} to N
Please prove a) and b), thank you. + B is a bijection, then (a) (Theorem 8.32) Let A and B be sets such that A is countable. If f: A B is countable. (b) (Theorem 8.33) Every subset of a countable set is countable.1
1. Show that if A and B are countable sets, then AUB is countable. 2. Show that if An are finite sets indexed by positive integers, then Un An is countable. 3. Show that if A and B are countable sets, then A x B is countable. 4. Show that any open set in R is a countable union of open intervals. 5. Show that any function on R can have at most countable many local maximals. Us
all parts A-E please. Problem 8.43. For sake of a contradiction, assume the interval (0,1) is countable. Then there exists a bijection f : N-> (0,1). For each n є N, its image under f is some number in (0, 1). Let f(n) :-0.aina2na3n , where ain 1s the first digit in the decimal form for the image of n, a2 is the second digit, and so on. If f (n) terminates after k digits, then our convention will be...
4. Let n be a positive integer. Z" is the set of all lists of length n whose entries are in Z. Prove that Z" is countable. (Hint: Find a bijection between Z"-1x Z and Z" and then use induction.) 4. Let n be a positive integer. Z" is the set of all lists of length n whose entries are in Z. Prove that Z" is countable. (Hint: Find a bijection between Z"-1x Z and Z" and then use induction.)
(5) Let A, B and C be sets. Show that there is a bijection between the sets F(A, B x C) and F(A, B) x F(A, C) (5) Let A, B and C be sets. Show that there is a bijection between the sets F(A, B x C) and F(A, B) x F(A, C)
e finite dimensional vector Spaces, dim Show that there is a bijection between the set Bil(V,W;R) of all bilinear functions on V and W and the set ĢLn(m)R of all matrices of order n x m. e finite dimensional vector Spaces, dim Show that there is a bijection between the set Bil(V,W;R) of all bilinear functions on V and W and the set ĢLn(m)R of all matrices of order n x m.
12) Let S1 be a countable set, S2 a set that is not countable, and S1 ⊂ S2. a) Show that S2 must then contain an infinite number of elements that are not in S1. b) Show that in fact S2 − S1cannot be countable.