We prove that the set of all support points of a nonempty closed convex bounded set $C$ in a real infinite-dimensional Banach space $X$ is $\mathrm{AR(}\sigma$-$\mathrm{compact)}$ and contractible. Under suitable conditions, similar results are proved also for the set of all support functionals of $C$ and for the domain, the graph and the range of the subdifferential map of a proper convex l.s.c. function on $X$.

Keywords:

convex set, support point, support functional, absolute retract, Leray-Schauder continuation principle convex set, support point, support functional, absolute retract, Leray-Schauder continuation principle

MSC Classifications:

46A55, 46B99, 52A07 show english descriptions Convex sets in topological linear spaces; Choquet theory [See also 52A07]
None of the above, but in this section
Convex sets in topological vector spaces [See also 46A55] 46A55 - Convex sets in topological linear spaces; Choquet theory [See also 52A07]
46B99 - None of the above, but in this section
52A07 - Convex sets in topological vector spaces [See also 46A55]

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