A full characterization of stable unit balls in Orlicz spaces. (English) Zbl 0772.46012

A convex subset \(C\) of a topological vector space is called stable if the midpoint map \(\varphi_{1/2}: C\times C\to C\) is open, where \(\varphi_{1/2}(x,y)={1\over 2}(x+y)\). The author gives a full characterization of stable unit balls in Orlicz spaces.


46E30 Spaces of measurable functions (\(L^p\)-spaces, Orlicz spaces, Köthe function spaces, Lorentz spaces, rearrangement invariant spaces, ideal spaces, etc.)
46B20 Geometry and structure of normed linear spaces
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