Bourbaki

Exercise 39, § 2

Topological Vector Spaces, II, p. 71

Let E be a finite dimensional Hausdorff topological vector space. a) Let F(E)\mathfrak{F}(E) be the family of closed non-empty sets of E, carrying the uniform structure deduced from the uniform structure of E by the procedure of GT, II, § 1, exerc. 5, a). Show that, the set C(E)\mathfrak{C}(E) of non-empty closed convex sets of E, is closed in the space F(E)\mathfrak{F}(E). Deduce that if K is a compact set in E, the set of non-empty closed convex sets in E that are contained in K, is a compact set in C(E)\mathfrak{C}(E) (cf.cf. GT, § 4, exerc. 11). b) Let K0(E)\mathfrak{K}_0(E) be the set of compact convex subsets of E that contain 0 as an interior point. For every set A∈K0(E)A \in \mathfrak{K}_0(E), let pAp_A be the gauge of A (II, p. 20). Show that A↦pAA \mapsto p_A is an isomorphism of the uniform subspace K0(E)\mathfrak{K}_0(E) of C(E)\mathfrak{C}(E) on a subspace of the space Cc(E;R)\mathscr{C}_c(E; \mathbf{R}) of continuous real valued functions in E, carrying the uniform structure of compact convergence (GT, X, § 1.6).

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