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Nuclear Fréchet spaces with locally round finite dimensional decomposition. (English) Zbl 0536.46005
A class of finite dimensional decompositions (FDDs), called locally round, is introduced in Fréchet spaces. A Fréchet space with a locally round FDD can be viewed as a generalization of a Köthe space. The block subspaces and block quotients of such a space are always complemented and have a basis. Conversely, sometimes these properties characterize an FDD being locally round.

##### MSC:
 46A45 Sequence spaces (including Köthe sequence spaces) 46A35 Summability and bases in topological vector spaces 46A13 Spaces defined by inductive or projective limits (LB, LF, etc.) 46A11 Spaces determined by compactness or summability properties (nuclear spaces, Schwartz spaces, Montel spaces, etc.) 46A04 Locally convex Fréchet spaces and (DF)-spaces
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##### References:
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