Some open problems on best approximation in normed linear spaces
Ivan Singer (1966-1967)
Séminaire Choquet. Initiation à l'analyse
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Displaying similar documents to “Another characterization of Hilbert spaces”
Some open problems on best approximation in normed linear spaces
Special symmetries of Banach spaces isomorphic to Hilbert spaces
Jarno Talponen (2010)
Studia Mathematica
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We characterize Hilbert spaces among Banach spaces in terms of transitivity with respect to nicely behaved subgroups of the isometry group. For example, the following result is typical: If X is a real Banach space isomorphic to a Hilbert space and convex-transitive with respect to the isometric finite-dimensional perturbations of the identity, then X is already isometric to a Hilbert space.
All separable Banach space admit for every ε>0 fundamental total and bounded by 1 + ε biorthogonal sequences
A. Pełczyński (1976)
Studia Mathematica
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On intersections of similar sets
Grünbaum, Branko (1959)
Portugaliae mathematica
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Addendum and corrigendum to the paper "Some applications of Zygmund's lemma to non-linear differential equations in Banach and Hilbert spaces" (Studia Math., 44 (1972), pp. 335-344)
T. Flett (1972)
Studia Mathematica
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For a Banach space isomorphic to its square the Radon-Nikodým property and the Krein-Milman property are equivalent
Walter Schachermayer (1985)
Studia Mathematica
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Directionally Euclidean structures of Banach spaces
Jarno Talponen (2011)
Studia Mathematica
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We study Banach spaces with directionally asymptotically controlled ellipsoid-approximations of the unit ball in finite-dimensional sections. Here these ellipsoids are the unique minimum volume ellipsoids, which contain the unit ball of the corresponding finite-dimensional subspace. The directional control here means that we evaluate the ellipsoids by means of a given functional of the dual space. The term 'asymptotical' refers to the fact that we take 'lim sup' over finite-dimensional...
Direct sums of Cartan factors
Carlo Petronio (1992)
Rendiconti del Seminario Matematico della Università di Padova
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Transitivity of the norm on Banach spaces.
Julio Becerra Guerrero, A. Rodríguez-Palacios (2002)
Extracta Mathematicae
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Dentability and finite-dimensional decompositions
J. Bourgain (1980)
Studia Mathematica
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Isomorphic characterizations of Hilbert spaces by orthogonal series with vector valued coefficients
S. Kwapien (1972-1973)
Séminaire Analyse fonctionnelle (dit "Maurey-Schwartz")
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