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Category Archives: Topology
Hausdorff metric compatible with Vietoris topology / Kechris p25 B Ex 4.21
Kechris, p. 25 (B) Exercise (4.21). Show that the Hausdorff metric is compatible with the Vietoris topology. Proof. Let be a metric space with . Let denote the topology from the Hausdorff metric on , with basis , denote the … Continue reading
Posted in Analysis, Descriptive Set Theory, Kechris, Topology
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Vietoris topology and Hausdorff metric
From Kechris: Let be a topological space. We denote by the space of all compact subsets of equipped with the Vietoris topology. Let be a metric space with . We define the Hausdorff metric on , , as follows: , … Continue reading
Posted in Analysis, Definition, Descriptive Set Theory, Kechris, Topology
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Questions
I have been unable to solve the following problems from Kechris. Any hints, advice, or solutions would be appreciated. 1. Exercise 4.9: Let be separable Banach spaces. The weak topology on is the one generated by the functions (from into … Continue reading
Posted in Analysis, Descriptive Set Theory, Kechris, Metric Spaces, Topology, Unsolved
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A complete, compatible metric for the strong topology (p15 (A))
Let be separable Banach spaces over . Show that the following is a complete, compatible metric for the strong topology on : where is a dense sequence in the unit ball of . Proof. It is not difficult to check … Continue reading
Any subspace of a separable metric space is separable
Let be a separable, metric space, , and let be countable and dense. For each , choose if such intersection is nonempty. Then, is a countable subset of . Let . Then choose . Now, choose such that . Then, , so … Continue reading
Posted in Metric Spaces, Separability, Topology
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