We define the set X ⊆ L^∞ by X = { {xn} ∈ L^∞ : lim n→∞ xn = 1 }
Prove that the set X with the subspace metric d∞|X×X is a complete metric space.
We define the set X ⊆ L^∞ by X = { {xn} ∈ L^∞ : lim n→∞ xn = 1 } Prove that the set X with the subspace metric d∞|X×X is a complete metric space.
the set of compactly supported sequences is defined by c00 = {{xn} : there exists some N ≥ 0 so that xn = 0 for all n ≥ N } Prove that for 1 ≤ p ≤ ∞ the metric space (c00, dp) is not complete.
In this problem we show that any metric space (X, d) is homeomorphic to a bounded metric space. (a) Define ρ : X X R by Show that ρ defines a metric on X. Conclude that (X,p) is a bounded metric space. (b) Show that f : (X, d) → (X, p) given by f(x) = x is a homeomorphism ism. (c) Is it true that if (X, d) is complete then (X, ρ) is complete?
In this problem we...
3. Suppose X is a metric space with a sequence of points Xn e X with the property that for each n + m we have d(Xn, Xm) = 1. Prove that no subsequence of xn converges, and that therefore X is not compact. Hint: You could use the previous problem.
(5) Here is a fascinating equivalence for being a complete metric space that we will use later. Let (X,d) be a metric space. (b) ** (10 points) Show that the following are equivalent: • (X, d) is complete; • for every family of non-empty closed subsets Fo, F1, F2, ... of X such that F, 2 F12 F22... and limn700 diam( Fn) = 0, it holds that Nnen Fn = {a} for some a € X. (Hint: for the reverse...
(a) Let (X, d) be a metric space. Prove that the complement of any finite set F C X is open. Note: The empty set is open. (b) Let X be a set containing infinitely many elements, and let d be a metric on X. Prove that X contains an open set U such that U and its complement UC = X\U are both infinite.
the set A ⊆ L^2 by A = { {xn} ∈ L^ 2 : X∞ n=0 (1 + n)|xn| 2 ≤ 1 } Prove A is totally bounded, and compact.
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...
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....
8) Prove that C([O, 1]) is a metric space with the metric .1 d(f, g) = / If(x)-g(x)| dx. 9) Let (X, di) and (Y, d2) be metric spaces. a) Prove that X × Y is a metric space with the metric b) Prove that X x Y is a metric space with the metric
8. Let {Xn, n = 1, 2, . . . } and (, , n = 1, 2, . . . } be two sequences of random variables, defined on the sample space Suppose that we know . Xn → X, G.8 Prove that XnYX+Y.
8. Let {Xn, n = 1, 2, . . . } and (, , n = 1, 2, . . . } be two sequences of random variables, defined on the sample space Suppose that...