4. Let A be a non-empty set and f: A- A be a function. (a) Prove that f has a left inverse in FA if and only if f is injective (one-to-one) (b) Prove that, if f is injective but not surjective (which means that the set A is infinite), then f has at least two different left inverses.
Let A and B be two non-empty bounded sets, and A and B are disjoint. Is sup(A U B) = sup(A) + sup(B)? Prove if true, and give a counter example if not.
For nonempty sets A, B and C, let f : A → B and g : B → C be functions. Prove that if g ◦ f is injective, then f is injective
A. (Leftovers from the Proof of the Pigeonhole Principle). As before, let A and B be finite sets with A! 〉 BI 〉 0 and let f : A → B be any function Given a A. let C-A-Va) and let D-B-{ f(a)} PaRT A1. Define g: C -> D by f(x)-g(x). Briefly, if g is not injective, then explain why f is not injective either. Let j : B → { 1, 2, 3, . . . , BI}...
= Q 6. Let f: {0,1} + {0,1} be a function given by f(0) = 0 = f(1). Find two (total) functions g: {0,1} +{0,1} and h: {0,1} +{0,1} such that fog #gof and foh= hof. Write out f and your chosen functions g and h in table form, using a single table. Only the table is required as the answer.
need help with proving discrete math HW, please try write clearly and i will give a thumb up thanks!! Let A and be B be sets and let f:A B be a function. Define C Ax A by r~y if and only if f(x)f(y). Prove thatis an equivalence relation on A. Let X be the set of~-equivalence classes of A. L.e. Define g : X->B by g(x) Prove that g is a function. Prove that g is injective. Since g...
1. Prove that the function f: X → Y is injective if and only if it satisfies the following condition: For any set T and functions g: T → X and h : T → X, o g = f o h implies g = h.
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.
4. Let X and Y be any sets and let F be any one-to-one (injective) function from X to Y. Prove that for every subset A CX: (a) (10 points) AC F-(F(A)). (b) (10 points) F-1(F(A)) C A.