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The problem of isometric extension on the unit sphere of the space \(l\cap l^p(H)\) for \(0 < p < 1\). (English) Zbl 1330.46006

Summary: In this paper, we study the problem of isometric extension on the unit sphere of the space \(l\cap l^p(H)\) for \(0<p<1\). We obtain that an isometric mapping of the unit sphere \(S(l\cap l^p(H))\) onto itself can be extended to an isometry on the whole space \(l\cap l^p(H)\).

MSC:

46A16 Not locally convex spaces (metrizable topological linear spaces, locally bounded spaces, quasi-Banach spaces, etc.)
46B04 Isometric theory of Banach spaces
46E40 Spaces of vector- and operator-valued functions