Equivariant generalization of Dugundji's theorem (Q1083081)

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scientific article; zbMATH DE number 3975904
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Equivariant generalization of Dugundji's theorem
scientific article; zbMATH DE number 3975904

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    Equivariant generalization of Dugundji's theorem (English)
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    1985
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    The author provides an equivariant generalization of Dugundji's extension of Tietze's theorem. The main result of this paper is the following: Theorem. Let G be a compact Lie group, A an invariant closed subset of the metrizable G-space X, and V a convex invariant subset of some locally convex G-space Z. Then each equivariant map \(f: A\to V\) admits an equivariant extension \(F: L\to V\) to some invariant neighbourhood L of the set A in X. The author shows by an example that F cannot be defined on all of X, in general. If, though, the set \(\{\) \(v\in V:\) \(gv=v\) for all \(g\in G\}\) is nonempty, then \(L=X\). Also, if V is a complete set with respect to the natural group of uniformities of the linear topological space Z, then \(L=X\).
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    Dugundji's theorem
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    invariant subset of locally convex G-space
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    compact Lie group
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    equivariant map
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    equivariant extension
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