i) Does Lebesgue lemma hold true in the plane? Justify your answer!
ii) Let (X, d1) be a compact metric space and (Y, d2) a metric space. Suppose that f : X → Y is continuous. Use Lebesgue lemma to show that for every > 0 there exists δ > 0 such that if d1(x, y) < δ then d2(f(x), f(y)) < , that is, f is uniformly continuous.
i) Does Lebesgue lemma hold true in the plane? Justify your answer! ii) Let (X, d1) be a compact metric space and (Y, d2) a metric space. Suppose that f : X → Y is continuous. Use Lebesgue lemma to sh...
Let (X, d) be a compact metric space, and con- sider continuous functions fk : X → R, for k N, and f : X → R. Suppose that, for each the sequence (fe(x))ke N 1s a monotonic sequence which converges to (x). Show that r є X, k)kEN Converges to j uniformly.
Let (X, d) be a compact metric space, and con- sider continuous functions fk : X → R, for k N, and f : X → R....
* Exercise 10. Let M be a (non-empty) compact metric space and f: M → M a continuous map such that for every ε > 0 there exists x E M such that d(f(x), z) < E. Show that there exists y M such that f()y Hint: consider the map g: MR defined by g(x)=d(f(x),z).] [8 marks]
4. Let Uαα∈A be a finite open cover
of a compact metric space X. For question for (a), (b)
Remark: ε is called a Lebesgue number of the cover.
(a) Show that there exists ε>0 such that for each
x∈X, the open ball B(x;ε) is contained in one of
the Uα’s.
(b) Show that if at least one of the Uα’s is a
proper subset of X, then there is a largest Lebesgue
number for the cover.
4. Let {U}aea...
A subset D of a metric space (X, d) is dense if every member of
X is a limit of a sequence of elements from D.
Suppose (X,d) and (Y,ρ) are metric spaces and D is a dense
subset of X.
1. Prove that if f : D -» Y is uniformly continuous then there exists an extension15 of f to a if dn (E D) e X define 7(x) lim f(d,) uniformly continuous function f:X * Y. Hint: 2....
Prove:
By taking the following problem as being given/true :
(Analysis on Metric Spaces)
Let f : [0, 1] x [0, 1] + R be defined by f(x,y) = ſi if y=x? if y #r? Show that f is integrable on [0, 1] x [0,1]. Let f : [0, 1] + R be uniformly continuous, so that for every e > 0, there exists 8 >0 such that -y<= f(x) - f(y)< € for every I, Y E (0,1). The...
For metric spaces and topology
Problem II. a) Show that f: X →Y is continuous if and only if f-'(C) CX is closed for every closed C CY b) Then show that a function f: X + Y is continuous if and only if f(A) < f(A) for all ACX
Let f: [0,1]→R be uniformly continuous, so that for every >0,
there exists δ >0 such that |x−y|< δ=⇒|f(x)−f(y)|< for
every x,y∈[0,1].The graph of f is the set G f={(x,f(x))
:x∈[0,1]}.Show that G f has measure
zero
Let f : [0, 1] → R be uniformly continuous, so that for every e > 0, there exists 8 >0 such that 2- y<83|f() - f(y)< € for every 1, 9 € [0,1]. The graph of f is the set Gj =...
3. Suppose that (M, ρ) is a compact metric space and f : (M, p)-+ (M,p) is a function such that (Vz, y E M) ρ (z, y) ρ (f (x), f (y)). a. Let x E (M, ρ) and consider the sequence of points {f(n) (X)}n 1 . (Remember: fn) denotes the composition of f with itself, n times, so for each n, f+() rn, k E N) such that ρ (f(m) (x) ,f(n +k) (r)) < ε ....
Problem II. i) Let Tı and T2 be two topologies on the same space X. Suppose that T2 is finer than η. If (X,n) is compact, does it follow that (X,2) is compact? Conversely, if (X, T2) is compact, does it follow that (X, Ti) is compact? la. ii) Let Y C X be equipped with the subspace topology. Show that Y is compact in the subspace topology if and only if any cover of Y with open sets in...
B2. (a) Let I denote the interval 0,1 and let C denote the space of continuous functions I-R. Define dsup(f,g)-sup |f(t)-g(t) and di(f.g)f (t)- g(t)ldt (f,g E C) tEI (i) Prove that dsup is a metric on C (ii) Prove that di is a metric on C. (You may use any standard properties of continuous functions and integrals, provided you make your reasoning clear.) 6 i) Let 1 denote the constant function on I with value 1. Give an explicit...