 # metric spaces homework solutions

For instance, R \mathbb{R} R is complete under the standard absolute value metric, although this is not so easy to prove. Solution. Solution: It is clear that D(x,y) ≥ 0, D(x,y) = 0 if and only if x = y, and D(x,y) = D(y,x). Let X be a metric space and C(X) the collection of all continuous real-valued functions in X. It remains to show that D satisﬁes the triangle inequality, D(x,z) ≤ D(x,y)+D(y,z). math; advanced math; advanced math questions and answers (a) State The Stone-Weierstrass Theorem For Metric Spaces. [0;1] de ned by f a(t) = (1 if t= a 0 if t6=a There are uncountably many such f a as [0;1] is uncountable. Whatever you throw at us, we can handle it. Assume there is a constant 0 < c < 1 so that the sequence xk satis es d(xn+1; xn) < cd(xn; xn 1) for all n = 1;2;:::: a) Show that d(xn+1;xn) < cnd(x1;x0). Home. R is an ultra-metric if it satis es: (a) d(a;b) 0 and d(a;b) = 0 if and only a= b. mapping metric spaces to metric spaces relates to properties of subsets of the metric spaces. (b) Prove that if Y is complete, then Y is closed in X. De¿nition 5.1.1 Suppose that f is a real-valued function of a real variable, p + U, and there is an interval I containing p which, except possibly for p is in the domain of f . Solution. Let X D.0;1“. SOLUTIONS to HOMEWORK 2 Problem 1. Solution: (a) Assume that there is a subset B of A such that B is open, A ⊂ B, and A 6= B. in the uniform topology is normal. Solution. Introduction Let X be an arbitrary set, which could consist of vectors in Rn, functions, sequences, matrices, etc. NOTES ON METRIC SPACES JUAN PABLO XANDRI 1. f a: [0;1] ! Solutions to Homework #7 1. Proof. Let Mbe a compact metric space and let fx ngbe a Cauchy sequence in M. By Theorem 43.5, there exists a convergent subsequence fx n k g. Let x= lim k!1 x n k. Since fx ngis Cauchy, there exists some Nsuch that m;n Nimplies d(x m;x n) < 2. Hint: It is metrizable in the uniform topology. Homework 2 Solutions - Math 321,Spring 2015 (1)For each a2[0;1] consider f a 2B[0;1] i.e. Give an open cover of B1 (0) with no finite subcover 59. Prove that a compact metric space is complete. Defn A sequence {x n} in a metric space (X,d) is said to converge, to a point x 0 say, if for each neighborhood of x 0 there exists a natural number N so that x n belongs to the neighborhood if n is greater or equal to N; that is, eventually the sequence is contained in the neighborhood. (xxv)Every metric space can be embedded isometrically into a complete metric space. In the category of metric spaces (with Lipschitz maps having Lipschitz constant 1), the product (in the category theory sense) uses the sup metric. Metric Spaces MT332P Problems/Homework/Notes Recommended Reading: 1.Manfred Einsiedler, Thomas Ward, Functional Analysis, Spectral Theory, and Applications What could we say about the properties of the metric spaces i described above in the spirit of the description of the continuity of the real line? Let F n.0;1=n“for all n2N. For Euclidean spaces, using the L 2 norm gives rise to the Euclidean metric in the product space; however, any other choice of p will lead to a topologically equivalent metric space. Prove that none of the spaces Rn; l1;l2; c 0;or l1is compact. Question: (a) State The Stone-Weierstrass Theorem For Metric Spaces. The “largest” and the ‘smallest” are in the sense of inclusion ⊂. 46.7. 1 Distance A metric space can be thought of as a very basic space having a geometry, with only a few axioms. Show that the functions D(x,y) = d(x,y) 1+d(x,y) is also a metrics on X. The case of Riemannian manifolds. Problem 4.10: Use the fact that infinite subsets of compact sets have limit points to give an alternate proof that if X and Z are metric spaces with X compact, and f: X → Z is continuous, then f is uniformly continuous. Is it a metric space and multivariate calculus? Note: When you solve a problem about compactness, before writing the word subcover you need to specify the cover from which this subcover is coming from 58. Metric spaces are generalizations of the real line, in which some of the theorems that hold for R remain valid. The Attempt at a Solution It seems so because all the metric properties are vacuously satisfied. Metric Spaces Joseph Muscat2003 (Last revised May 2009) (A revised and expanded version of these notes are now published by Springer.) Math 104 Homework 3 Solutions 9/13/2017 3.We use the Cauchy{Schwarz inequality with b 1 = b 2 = = b n= 1: ja 1 1 + a 2 1 + + a n 1j q a2 1 + a2 2 + + a2 p n: On the other hand, ja 1 1 + a 2 1 + + a n1j= ja 1 + a 2 + + a nj 1: Combining these two inequalities we have 1 q a 2 1 + a 2 + + a2n p Let us write D for the metric topology on … Let Xbe a metric space and Y a subset of X. 1 ) 8 " > 0 9 N 2 N s.t. (xxiv)The space R! Show that: (a) A is the largest open set contained in A. Homework Statement Is empty set a metric space? x 1 (n ! (a) Prove that if Xis complete and Yis closed in X, then Yis complete. Hint: Homework 14 Problem 1. 5.1 Limits of Functions Recall the de¿nitions of limit and continuity of real-valued functions of a real vari-able. Consider R with the usual topology. Does this contradict the Cantor Intersection Theorem? 5.1.1 and Theorem 5.1.31. Recall that we proved the analogous statements with ‘complete’ replaced by ‘sequentially compact’ (Theorem 9.2 and Theorem 8.1, respectively). Knowing whether or not a metric space is complete is very useful, and many common metric spaces are complete. 4.4.12, Def. For n2P, let B n(0) be the ball of radius nabout 0 with respect to the relevant metric on X. 4.1.3, Ex. Let EˆY. Homework 7 Solutions Math 171, Spring 2010 Henry Adams 42.1. See, for example, Def. d(x n;x 1) " 8 n N . Thank you. The metric space X is said to be compact if every open covering has a ﬁnite subcovering.1 This abstracts the Heine–Borel property; indeed, the Heine–Borel theorem states that closed bounded subsets of the real line are compact. MATH 4010 (2015-16) Functional Analysis CUHK Suggested Solution to Homework 1 Yu Meiy P32, 2. The resulting measure is the unnormalized s-Hausdorff measure. I am not talking about the definition which is an abstraction, i am talking about the application of the definition like above in the real line. Compactness in Metric Spaces: Homework 5 atarts here and it is due the following session after we start "Completeness. Solutions to Homework 2 1. True. Let 0 = (0;:::;0) in the case X= Rn and let 0 = (0;0;:::) in the case X= l1; l2; c 0;or l1. The metric satisfies a few simple properties. Solution. Let X= Rn;l1;l2;c 0;or l1. Our arsenal is the leading maths homework help experts who have handled such assignments before and taught at various universities around the UK, the USA, and Canada on the same topic. If (x n) is Cauchy and has a convergent subsequence, say, x n k!x, show that (x n) is convergent with the limit x. Convergent sequences are defined (in arbitrary topological spaces in Munkres 2.17, specifically on page 98 - to get the definition of metric space, replace "for each open U" by "for each epsilon ball B(x,epsilon)" in the definition.). True. solution if and only if y?ufor every solution uof Au= 0. A metric space M M M is called complete if every Cauchy sequence in M M M converges. In a complete metric space M, let d(x;y) denote the distance. Solutions to Assignment-3 September 19, 2017 1.Let (X;d) be a metric space, and let Y ˆXbe a metric subspace with the induced metric d Y. In mathematics, a metric space is a set together with a metric on the set. Differential Equations Homework Help. As an example, consider X= R, Y = [0;1]. Let f: X !Y be continuous at a point p2X, and let g: Y !Z be continuous at f(p). (c)For every a;b;c2X, d(a;c) maxfd(a;b);d(b;c)g. Prove that an ultra-metric don Xis a metric on X. Let (M;d) be a complete metric space (for example a Hilbert space) and let f: M!Mbe a mapping such that d(f(m)(x);f(m)(y)) kd(x;y); 8x;y2M for some m 1, where 0 k<1 is a constant. (xxvi)Euclidean space Rnis a Baire space. (a)Show that a set UˆY is open in Y if and only if there is a subset V ˆXopen in Xsuch that U = V \Y. A function d: X X! View Test Prep - Midterm Review Solutions: Metric Spaces & Topology from MTH 430 at Oregon State University. 5. Similar to the proof in 1(a) using the fact that ! A metric space is a set X together with a function d (called a metric or "distance function") which assigns a real number d(x, y) to every pair x, y X satisfying the properties (or axioms): d(x, y) 0 and d(x, y) = 0 x = y, d(x, y) = d(y, x), d(x, y) + d(y, z) d(x, z). Let ( M;d ) be a metric space and ( x n)n 2 N 2 M N. Then we de ne (i) x n! 130 CHAPTER 8. Let X, Y, and Zbe metric spaces, with metrics d X, d Y, and d Z. Give an example of a bounded linear operator that satis es the Fredholm alternative. Let Xbe a set. Answers and Replies Related Topology and Analysis News on Phys.org. Let (x n)1 n=1 be a Cauchy sequence in metric space (X;d) which has a … Show that g fis continuous at p. Solution: Let >0 be given. Solution: Only the triangle inequality is not obvious. Banach spaces and Hilbert spaces, bounded linear operators, orthogonal sets and Fourier series, the Riesz representation theorem. Then fF ng1 nD1 is a descending countable collection of closed, … Spectrum of a bounded linear operator and the Fredholm alternative. Take a point x ∈ B \ A . Homework 3 Solutions 1) A metric on a set X is a function d : X X R such that For all x, We want to endow this set with a metric; i.e a way to measure distances between elements of X.A distanceor metric is a function d: X×X →R such that if we take two elements x,y∈Xthe number d(x,y) gives us the distance between them. This is to tell the reader the sentence makes mathematical sense in any topo-logical space and if the reader wishes, he may assume that the space is a metric space. The following topics are taught with an emphasis on their applicability: Metric and normed spaces, types of convergence, upper and lower bounds, completion of a metric space. Here are instructions on how to submit the homework and take the quizzes: Homework + Quiz Instructions (Typo: Quizzes are 8:30-8:50 am PST) Note: You can find hints and solutions to the book problems in the back of the book. Provide an example of a descending countable collection of closed, nonempty sets of real numbers whose intersection is empty. Let (X,d) be a metric space and let A ⊂ X. Since x= lim k!1 x n k, there exists some Kwith n It covers the topology of metric spaces, continuity, connectedness, compactness and product spaces, and includes results such as the Tietze-Urysohn extension theorem, Picard's theorem on ordinary differential equations, and the set of discontinuities of the pointwise limit of a sequence of continuous functions. In this case, we say that x 0 is the limit of the sequence and write x n := x 0 . Let (X,d) be a metric space, and let C(X) be the set of all continuous func-tions from X into R. Show that the weak topology deﬁned on X by the functions in C(X) is the given topology on X deﬁned by the metric. Find solutions for your homework or get textbooks Search. 0. Metric spaces and Multivariate Calculus Problem Solution. (b) A is the smallest closed set containing A. Problem 14. A “solution (sketch)” is too sketchy to be considered a complete solution if turned in; varying amounts of detail would need to be filled in. 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