# metric space pdf notes

Still, you should check the A metric space is called complete if every Cauchy sequence converges to a limit. A metric space is a pair (S, ρ) of a set S and a function ρ : S × S → R Proof. The third property is called the triangle inequality. 2.1. Deﬁnition. Let an element ˘of Xb consist of an equivalence class of Cauchy 251. TOPOLOGY: NOTES AND PROBLEMS Abstract. Let (X;d) be a metric space and let A X. Deﬁnition. Connectedness and Compactness: Connectedness, Connected subsets of R, Connectedness and continuous mappings, Compactness, Compactness and boundedness, Continuous functions on compact spaces. Topology of Metric Spaces: Open and closed ball, Neighborhood, Open set, Interior of a set, Limit point of a set, Derived set, Closed set, Closure of a set, Diameter of a set, Cantor’s theorem, Subspaces, Dense set. Notes of Metric Space Level: BSc or BS, Author: Umer Asghar Available online @ , Version: 1.0 METRIC SPACE:-Let be a non-empty set and denotes the set of real numbers. A metric space (X;d) is a … The second is the set that contains the terms of the sequence, and if stream %PDF-1.5 §1. d(f,g) is not a metric in the given space. Thus, Un U_ ˘U˘ ˘^] U‘ nofthem, the Cartesian product of U with itself n times. In other words, no sequence may converge to two diﬀerent limits. In these “Metric Spaces Notes PDF”, we will study the concepts of analysis which evidently rely on the notion of distance. Continuity & Uniform Continuity in Metric Spaces: Continuous mappings, Sequential criterion and other characterizations of continuity, Uniform continuity, Homeomorphism, Contraction mapping, Banach fixed point theorem. The limit of a sequence in a metric space is unique. x, then x is the only accumulation point of fxng1 n 1 Proof. Given a metric don X, the pair (X,d) is called a metric space. Therefore our de nition of a complete metric space applies to normed vector spaces: an n.v.s. In this course, the objective is to develop the usual idea of distance into an abstract form on any set of objects, maintaining its inherent characteristics, and the resulting consequences. A metric space is, essentially, a set of points together with a rule for saying how far apart two such points are: De nition 1.1. Metric Spaces A metric space is a set X endowed with a metric ρ : X × X → [0,∞) that satisﬁes the following properties for all x, y, and z in X: 1. ρ(x,y) = 0 if and only if x = y, 2. ρ(x,y) = ρ(y,x), and 3. ρ(x,z) ≤ ρ(x,y)+ ρ(y,z). These are the notes prepared for the course MTH 304 to be o ered to undergraduate students at IIT Kanpur. METRIC SPACES 3 It is not hard to verify that d 1 and d 1are also metrics on Rn.We denote the metric balls in the Euclidean, d 1 and d 1metrics by B r(x), B1 r (x) and B1 r (x) respectively. The discrete metric space. 4 0 obj We have provided multiple complete Metric Spaces Notes PDF for any university student of BCA, MCA, B.Sc, B.Tech CSE, M.Tech branch to enhance more knowledge about the subject and to score better marks in the exam. This distance function These notes are collected, composed and corrected by Atiq ur Rehman, PhD. (This is problem 2.47 in the book) Proof. x��]ms�F����7����˻�o�is��䮗i�A��3~I%�m���%e�\$d��N]��,�X,��ŗ?O�~�����BϏ��/�z�����.t�����^�e0E4�Ԯp66�*�����/��l��������W�{��{��W�|{T�F�����A�hMi�Q_�X�P����_W�{�_�]]V�x��ņ��XV�t§__�����~�|;_-������O>Φnr:���r�k��_�{'�?��=~��œbj'��A̯ Deﬁnition 1. Topology Generated by a Basis 4 4.1. A metric space X is called a complete metric space if every Cauchy sequence in X converges to some point in X. The ﬁrst goal of this course is then to deﬁne metric spaces and continuous functions between metric spaces. We motivate the de nition by means of two examples. Bounded sets in metric spaces. De nition 1.1. <>>> We will write (X,ρ) to denote the metric space X endowed with a metric ρ. 1 The dot product If x = (x Proof. (1.1) Together with Y, the metric d Y deﬁnes the automatic metric space (Y,d Y). Source: math.iitb.ac.in, Metric Spaces Notes Metric Spaces The following de nition introduces the most central concept in the course. Suppose x′ is another accumulation point. with the uniform metric is complete. This distance function is known as the metric. NOTES ON METRIC SPACES JUAN PABLO XANDRI 1. Then there is an automatic metric d Y on Y deﬁned by restricting dto the subspace Y× Y, d Y = dY| × Y. Let be a Cauchy sequence in the sequence of real numbers is a Cauchy sequence (check it!). We can easily convert our de nition of bounded sequences in a normed vector space into a de nition of bounded sets and bounded functions. Let X be a set and let d : X X !Rbe deﬁned by d(x;y) = (1 if x 6=y; 0 if x = y: Then d is a metric for X (check!) (M4) d( x, y ) d( x, z ) + d( z, y ). The purpose of this deﬁnition for a sequence is to distinguish the sequence (x n) n2N 2XN from the set fx n 2Xjn2Ng X. %���� 0:We write We are very thankful to Mr. Tahir Aziz for sending these notes. It helps to have a unifying framework for discussing both random variables and stochastic processes, as well as their convergence, and such a framework is provided by metric spaces. By the deﬁnition of convergence, 9N such that d„xn;x” <ϵ for all n N. fn 2 N: n Ng is inﬁnite, so x is an accumulation point. Basis for a Topology 4 4. Think of the plane with its usual distance function as you read the de nition. Metric Spaces, Open Balls, and Limit Points DEFINITION: A set , whose elements we shall call points, is said to be a metric space if with any two points and of there is associated a real number ( , ) called the distance from to . (M3) d( x, y ) = d( y, x ). Theorem. Ark1: Metric spaces MAT2400 — spring 2012 Subset metrics Problem 24. Proposition. NOTES FOR MATH 4510, FALL 2010 DOMINGO TOLEDO 1. A metric space is a pair ( X, d ), where X is a set and d is a metric on X; that is a function on X X such that for all x, y, z X, we have: (M1) d( x, y ) 0. Metric Spaces Then d is a metric on R. Nearly all the concepts we discuss for metric spaces are natural generalizations of the corresponding concepts for R with this absolute-value metric. Notes on Metric Spaces These notes introduce the concept of a metric space, which will be an essential notion throughout this course and in others that follow. MAT 314 LECTURE NOTES 1. (Tom’s notes 2.3, Problem 33 (page 8 and 9)). A metric space is a non-empty set equi pped with structure determined by a well-defin ed notion of distan ce. We have listed the best Metric Spaces Reference Books that can help in your Metric Spaces exam preparation: Student Login for Download Admit Card for OBE Examination, Step-by-Step Guide for using the DU Portal for Open-Book Examination (OBE), Open Book Examination (OBE) for the final semester/term/year students, Computer Algebra Systems & Related Software Notes, Introduction to Information Theory & Coding Notes, Mathematical Modeling & Graph Theory Notes, Riemann Integration & Series of Functions Notes. Many mistakes and errors have been removed. ?�ྍ�ͅ�伣M�0Rk��PFv*�V�����d֫V��O�~��� Metric Spaces Handwritten Notes These are not the same thing. In this course, the objective is to develop the usual idea of distance into an abstract form on any set of objects, maintaining its inherent characteristics, and the resulting consequences. 1 An \Evolution Variational Inequality" on a metric space The aim of this section is to introduce an evolution variational inequality (EVI) on a metric space which will be the main subject of these notes. 1 Metric spaces IB Metric and Topological Spaces 1 Metric spaces 1.1 De nitions As mentioned in the introduction, given a set X, it is often helpful to have a notion of distance between points. NOTES ON METRIC SPACES JUAN PABLO XANDRI 1. Recall that every normed vector space is a metric space, with the metric d(x;x0) = kx x0k. called a discrete metric; (X;d) is called a discrete metric space. Some of this material is contained in optional sections of the book, but I will assume none of that and start from scratch. Metric Space (Handwritten Classroom Study Material) Submitted by Sarojini Mohapatra (MSc Math Student) Central University of Jharkhand ... P Kalika Notes (Provide your Feedbacks/Comments at maths.whisperer@gmail.com) Title: Metric Space Notes Author: P Kalika Subject: Metric Space Suppose that Mis a compact metric space and that SˆMis a closed subspace. Let ϵ>0 be given. Analysis on metric spaces 1.1. Name Notes of Metric Space Author Prof. Shahzad Ahmad Khan Send by Tahir Aziz Since is a complete space, the sequence has a limit. <> 2 0 obj View Notes - notes_on_metric_spaces_0.pdf from MATH 321 at Maseno University. endobj Product Topology 6 6. <>/Font<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> 252 Appendix A. Source: spcmc.ac.in, Metric Spaces Handwritten Notes 2 Open balls and neighborhoods Let (X,d) be a metric space… In nitude of Prime Numbers 6 5. Then ε = 1 2d(x,y) is positive, so there exist integers N1,N2 such that d(x n,x)< ε for all n ≥ N1, d(x n,y)< ε for all n ≥ N2. Introduction Let X … Suppose {x n} is a convergent sequence which converges to two diﬀerent limits x 6= y. 1.1 Metric Space 1.1-1 Definition. Remark 3.1.3 From MAT108, recall the de¿nition of an ordered pair: a˛b def … Notes of Metric Spaces These notes are related to Section IV of B Course of Mathematics, paper B. Let (X,d) denote a metric space, and let A⊆X be a subset. It is easy to check that satisfies properties .Ðß.Ñ .>> >1)-5) so is a metric space. The same set can be … Source: princeton.edu. Topological Spaces 3 3. Metric Spaces (Notes) These are updated version of previous notes. A ball B of radius r around a point x ∈ X is B = {y ∈ X|d(x,y) < r}. Suppose dis a metric on Xand that Y ⊆ X. Example 7.4. Source: daiict.ac.in, Metric Spaces Handwritten Notes Deﬁne d: R2 ×R2 → R by d(x,y) = (x1 −y1)2 +(x2 −y2)2 x = (x1,x2), y = (y1,y2).Then d is a metric on R2, called the Euclidean, or ℓ2, metric.It corresponds to And by replacing the norm in the de nition with the distance function in a metric space, we can extend these de nitions from normed vector spaces to general metric spaces. De nition (Metric space). endobj 94 7. (M2) d( x, y ) = 0 if and only if x = y. If xn! spaces and σ-ﬁeld structures become quite complex. B r(x) is the standard ball of radius rcentered at xand B1 r (x) is the cube of length rcentered at x. Metric spaces Lecture notes for MA2223 P. Karageorgis pete@maths.tcd.ie 1/20. The topics we will cover in these Metric Spaces Notes PDF will be taken from the following list: Basic Concepts: Metric spaces: Definition and examples, Sequences in metric spaces, Cauchy sequences, Complete metric space. A useful metric on this space is the tree metric, d(x,y) = 1 min{n: xn ̸= yn}. Therefore ‘1is a normed vector space. If a metric space Xis not complete, one can construct its completion Xb as follows. Incredibly, this metric makes the Baire space “look” just like the space of irrational numbers in the unit interval [1, Theorem 3.68, p. 106]. Introduction Let X be an arbitrary set, which could consist of vectors in Rn, functions, sequences, matrices, etc. endobj The term ‘m etric’ i s d erived from the word metor (measur e). Already know: with the usual metric is a complete space. ���A��..�O�b]U*� ���7�:+�v�M}Y�����p]_�����.�y �i47ҨJ��T����+�3�K��ʊPD� m�n��3�EwB�:�ۓ�7d�J:��'/�f�|�r&�Q ���Q(��V��w��A�0wGQ�2�����8����S`Gw�ʒ�������r���@T�A��G}��}v(D.cvf��R�c�'���)(�9����_N�����O����*xDo�N�ׁ�rw)0�ϒ�(�8�a�I}5]�Q�sV�2T�9W/\�Y}��#�1\�6���Hod�a+S�ȍ�r-��z�s���. 1.2 Open Sets (in a metric space) Now that we have a notion of distance, we can deﬁne what it means to be an open set in a metric space. <> De nitions, and open sets. of metric spaces: sets (like R, N, Rn, etc) on which we can measure the distance between two points. METRIC SPACES, TOPOLOGY, AND CONTINUITY Lemma 1.1. Metric Spaces Notes PDF. Metric Spaces, Topological Spaces, and Compactness sequences in X;where we say (x ) ˘ (y ) provided d(x ;y ) ! In these “Metric Spaces Notes PDF”, we will study the concepts of analysis which evidently rely on the notion of distance. 74 CHAPTER 3. 3 0 obj We call the‘8 taxicab metric on (‘8Þ For , distances are measured as if you had to move along a rectangular grid of8œ# city streets from to the taxicab cannot cut diagonally across a city blockBC ). Source: iitk.ac.in, Metric Spaces Notes Deﬁnition 1.2.1. Contents 1. �?��No~� ��*�R��_�įsw\$��}4��=�G�T�y�5P��g�:҃l. 4 ALEX GONZALEZ A note of waning! A closed subspace of a compact metric space is compact. Topology of Metric Spaces 1 2. A function f: X!Y is said to be continuous if for any Uopen in Y, f 1(U) is open in X. Theorem 1.6.2 Let X, Y be topological spaces, and f: X!Y, then TFAE: Let X be a metric space. Students can easily make use of all these Metric Spaces Notes PDF by downloading them. METRIC SPACES 5 Remark 1.1.5. Lecture Notes on Metric Spaces Math 117: Summer 2007 John Douglas Moore Our goal of these notes is to explain a few facts regarding metric spaces not included in the ﬁrst few chapters of the text , in the hopes of providing an easier transition to more advanced texts such as . The deﬁnition of a metric Deﬁnition – Metric A metric on a set X is a function d that assigns a real number to each pair of elements of X in such a way that the following properties hold. 1.6 Continuous functions De nition 1.6.1 Let X, Y be topological spaces. METRIC SPACES AND SOME BASIC TOPOLOGY De¿nition 3.1.2 Real n-space,denotedUn, is the set all ordered n-tuples of real numbers˚ i.e., Un x1˛x2˛˝˝˝˛xn : x1˛x2˛˝˝˝˛xn + U . is complete if it’s complete as a metric space, i.e., if all Cauchy sequences converge to elements of the n.v.s. 1 0 obj 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.