# completion of metric space

Given an incomplete metric spaceM, we must somehow deﬁne a larger complete space in whichMsits. Completion of a metric space A metric space need not be complete. 5 0 obj << Denote by C [X] the collection of all Cauchy sequences in X. >> /Length 4396 The procedure is as follows. Proof. That is, we will construct a new metric space, (E;d), which is complete and contains our original space Ein some way (to be made precise later). Let (X;d X) be a complete metric space and Y be a subset of X:Then (Y;d Y) is complete if and only if Y is a closed subset of X: Proof. The resulting space will be denoted by Xand will be called the completion of Xwith respect to d. The hard part is that we have nothing to work with except Xitself, and somehow it Let (X, d) be a metric space. Theorem 1. It has the following universal property: if N is any complete metric space and f is any uniformly continuous function from M to N, then there exists a unique uniformly continuous function f′ from M′ to N that extends f. The space M' is determined up to isometry by this property (among all complete metric spaces isometrically containing M), and is called the completion of M. FunctionalAnalysis Topic035 Examples Completion of Metric Space in urdu/hindi x���r��}�Bٗ�31K܉t�Ҵi�i;m�3��fh �YS�CRq���������V�'� �˹ߠtu�JW{�.���ͫ?~�̊�DH�Wo�W,�Y��&�d�7�����[wq)�ZQ��K�uE��5����O�5ņ����w����0�Z�4��e8�����ru�aME��u�6��S��Gc�2�e?���\��tq�����"�&�qw ��������K%U89����[�z�[׆�Uݹ��E��j���U�5�MG����-m N���x��d"QN�0p{q)����ˋ����1�4|���Tµ�C�'�M���_���jKݓ]pd��n���./K�v��L�4E�߸������w5�ꂭ=��U�>\p�� :�'Fdii��M&l�µ�C�u��d�޾��Þ��P��]����1���+��#.��o^���� �+�tb�]i�e�j�{��]���˯Wi"�^=����E�,W߾���a�\�\$��Sx�f=j=jNd��CM~B1�0��ug�\(��}fJ�q� W� �J�iă�8��ǯ���� �S�"E��YW���=��J�hӟ)E�@)0�m�l�u�7a%�ٸ�mz.����#h�ҹ-*��~��+ ��. 1. Theorem 1. The Completion of a Metric Space Brent Nelson Let (E;d) be a metric space, which we will reference throughout. Every metric space has a completion. The Completion of a Metric Space Let (X;d) be a metric space. ʳ6��e�V�������/,����ee[W3���]1+�?�� f�'���Y�"��'Sn���O�}]����Zx����r��4�e3���_��V����V��D��*fd��8#9�i����T���6ϳ��@%y� C2?��kXqV�?����~�����YV�%��m��/������ 2���K�.oJ��,��.���v�ٶ�z*%�2�Zoڲ�ͪ�S���v[�S&S% �H�8�w�W��B_E�*��7f�u���Y���V0�� 9��q�C��y�p&!��J���j�J"�u�H>܇�[���W"�������nP��y�q��fL����Wo�>]1X���VN�����u��z��N��� %ɽ빚hb���r���A?�4�#iI��cB�Mk����P��M�hՑi�H�i,��tA�@;A"��"dV����e�-�u��־Ϧ�n�u�������["���#\�ءZ��6�����|�7��N���Ϫ���]]Ϊ&�,ڲ�2�&�ɘ\$B���!��0p��j+�G� q��� This is left to the reader as an exercise. >> /Length 3939 �:��k�,W��QxrSoV�� ���8�Q�y@��]\$��2�6{�q�K��M�'\$,� Then the closure ofMin this larger space is deﬁned to be its completion. stream %PDF-1.5 0, ‘1and ‘2, and to the general construction of completing a metric space. The purpose of these notes is to guide you through the construction of the \completion" of (E;d). << For example, let B = f(x;y) 2R2: x2 + y2 <1g be the open ball in R2:The metric subspace (B;d B) of R2 is not a complete metric space. A completion of a metric space (X,d) is a pair consisting of a complete metric space (X∗,d∗) and an isometry ϕ: X → X∗such that ϕ[X] is dense in X∗. Completion of a Metric Space Definition. C1b8�8�H���� �Ъ��/qs,�e���\����EH %���� Every metric space has a completion. x��[I�۸���P�ĮXV�ˇ̌g��U�*��}�%v�-m�r���y Z���r!���m ��N���+z���۫���Ԅi���7frb���\$R䓷�ɻ����� %���� stream Proposition 1.1. For instance: Bolzano{Weierstrass theorem. A completion of a metric space (X, d) is a pair consisting of a complete metric space (X *, d *) and an isometry ϕ: X → X * such that ϕ [X] is dense in X *. For any metric space M, one can construct a complete metric space M′ (which is also denoted as M), which contains M as a dense subspace. The new space is referred to as thecompletionof the space. @P���0������y]y��tX�ڎ����6�F)Q��}}d�cE�� }��8ھ�DS�Gj [����~�� ���������!�u��N)6,. Compactness in metric spaces The closed intervals [a;b] of the real line, and more generally the closed bounded subsets of Rn, have some remarkable properties, which I believe you have studied in your course in real analysis. /Filter /FlateDecode The goal of these notes is to construct a complete metric space which contains X as a subspace and which is the \smallest" space with respect to these two properties. 27 0 obj %PDF-1.5 /Filter /FlateDecode