Continuous version of the Choquet integral representation theorem
Piotr Puchała
Studia Mathematica, Tome 166 (2005), p. 15-24 / Harvested from The Polish Digital Mathematics Library

Let E be a locally convex topological Hausdorff space, K a nonempty compact convex subset of E, μ a regular Borel probability measure on E and γ > 0. We say that the measure μ γ-represents a point x ∈ K if sup||f||1|f(x)-Kfdμ|<γ for any f ∈ E*. In this paper a continuous version of the Choquet theorem is proved, namely, if P is a continuous multivalued mapping from a metric space T into the space of nonempty, bounded convex subsets of a Banach space X, then there exists a weak* continuous family (μt) of regular Borel probability measures on X γ-representing points in P(t). Two cases are considered: in the first case the values of P are compact, while in the second they are closed. For this purpose it is shown (using geometrical tools) that the mapping t ↦ ext P(t) is lower semicontinuous. Continuous versions of the Krein-Milman theorem are obtained as corollaries.

Publié le : 2005-01-01
EUDML-ID : urn:eudml:doc:284563
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     title = {Continuous version of the Choquet integral representation theorem},
     journal = {Studia Mathematica},
     volume = {166},
     year = {2005},
     pages = {15-24},
     zbl = {1077.46004},
     language = {en},
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Piotr Puchała. Continuous version of the Choquet integral representation theorem. Studia Mathematica, Tome 166 (2005) pp. 15-24. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm168-1-2/