Fragmentability of groups and metric-valued function spaces |
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Authors: | Petar S. Kenderov |
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Affiliation: | a Institute of Mathematics, Academy of Science, Bonchev-Street Block 8, 113 Sofia, Bulgaria b Department of Mathematics, The University of Auckland, Private Bag 92019, Auckland, New Zealand |
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Abstract: | Let (X,τ) be a topological space and let ρ be a metric defined on X. We shall say that (X,τ) is fragmented by ρ if whenever ε>0 and A is a nonempty subset of X there is a τ-open set U such that U∩A≠∅ and ρ−diam(U∩A)<ε. In this paper we consider the notion of fragmentability, and its generalisation σ-fragmentability, in the setting of topological groups and metric-valued function spaces. We show that in the presence of Baireness fragmentability of a topological group is very close to metrizability of that group. We also show that for a compact Hausdorff space X, σ-fragmentability of (C(X),‖⋅‖∞) implies that the space Cp(X;M) of all continuous functions from X into a metric space M, endowed with the topology of pointwise convergence on X, is fragmented by a metric whose topology is at least as strong as the uniform topology on C(X;M). The primary tool used is that of topological games. |
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Keywords: | 46B20 46B22 |
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