A representation formula for weakly compact starshaped sets


Abstract


Let S be a nonconvex weakly compact and weakly connected subset of a real locally convex topological linear space L and D a relatively weakly open subset of S containing the set Inc_{w}S of local nonconvexity points of S with respect to the weak topology. It is proved that kerS=\bigcap{\textrm{clconv} S_{z}: z ∈ D ∩ \,\textrm{reg} S}, where regS denotes the set of regular points of S and S_{z} = {s ∈ S: z \textrm{ is visible from} s \textrm{ via} S}. This substantially stregthens a recent result of Stavrakas in which the intersection above was taken over the whole set regS. The intersection formula is shown to hold also for a nonconvex connected weakly compact subset S of L with D being a relatively weakly open subset of S containing the set IncS of local nonconvexity points of S.

DOI Code: 10.1285/i15900932v19n2p207

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