1. Let A, B be two non-empty sets and f: A + B a function. We say that f satisfies the o-property if VC+0.Vg, h: C + A, fog=foh=g=h. Prove that f is injective if and only if f satisfies the o-property.
1. a) Let A = {2n|n ∈ ℤ} (ie, A is the set of even numbers) and define function f: ℝ → {0,1}, where f(x) = XA(x) That is, f is the characteristic function of set A; it maps elements of the domain that are in set A (ie, those that are even integers) to 1 and all other elements of the domain to 0. By demonstrating a counter-example, show that the function f is not injective (not one-to-one). b)...
1. (a) Let d be a metric on a non-empty set X. Prove that each of the following are metrics on X: a a + i. d(1)(, y) = kd(x, y), where k >0; [3] ii. dr,y) d(2) (1, y) = [10] 1+ d(,y) The proof of the triangle inequality for d(2) boils down to showing b + > 1fc 1+a 1+b 1+c for all a, b, c > 0 with a +b > c. Proceed as follows to prove...
6. Given a finite set A, denote IA] as a nurnber of elements in A. Let f : X → Y be a function with |XI, Yl< oo, i.e. X, Y are finite sets. Prove the following statements a) IXIS IYİ if f is injective. b) IY1S 1X1 if f is surjective. 6. Given a finite set A, denote IA] as a nurnber of elements in A. Let f : X → Y be a function with |XI, Yl
I. Functions and Isomorphisms. Let G be a group and let a EG be any non-identity element (so a #e). Define a function f : GG so that, for any r EG, f(x) = (xa)-1 (a) Is f injective? Prove your answer. (b) Is f surjective? Prove your answer. (c) Is f an isomorphism? Prove your answer.
answer question 5 please 3 and 4 are just included to refer to the theorems 3 Prove the following theorem: Theorem 2.2. Let S be a ser. The following statements are equivalent: (1) S is a countable set, i. e. there exists an injective function :S (2) Either S is the empty ser 6 or there exists a surjective function g: N (3) Either S is a finite set or there exists a bijective function h: N S (4) Prove...
How do I prove this function is not surjective? 3.) Let f: R-R, f(x)-x2+ x+1 and Show that f is not injective and not surjective Justify that g is bijective and find gt. PIR, Show all the wortky) Not Surtechive: fx) RB Surjective: ye(o,oo) hng (g) 8 gon)-es is bijecelive g(x)-ex+s
4·Let A and B be non-empty subsets of a space X. Prove that A U B is disconnected if A n B)U(A nB) 0. Prove that X is connected if and only if for every pair of non-empty subsets A and B of X such that X A U B we have (A B)U (An B)O.
4. Let A, B CR be non-empty open sets. Prove that AU B is an open set.
Let X = {0, 1, 2} and Y = {0,1,2}. Now we define f={(0,1),(1,0),(2,1)] Please enter your answer as a sum of the following numbers (they are not mutually exclusive): • 1 ifff is a function f : X Y • 2 ifff is a function and it is also injective • 4ifff is a function and it is also surjective This means that your answer can be 0 (not a function), 1 (a function but neither injective or surjective)....