Some characteristic and non-characteristic properties of inner product spaces
F. Javier Alonso Romero, Carlos Benítez Rodríguez (1986)
Extracta Mathematicae
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F. Javier Alonso Romero, Carlos Benítez Rodríguez (1986)
Extracta Mathematicae
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Carlos Benítez Rodríguez (1989)
Revista Matemática de la Universidad Complutense de Madrid
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Orthogonality in inner products is a binary relation that can be expressed in many ways without explicit mention to the inner product of the space. Great part of such definitions have also sense in normed linear spaces. This simple observation is at the base of many concepts of orthogonality in these more general structures. Various authors introduced such concepts over the last fifty years, although the origins of some of the most interesting results that can be obtained for these generalized...
Carlos Benítez, Krzysztof Przesławski, David Yost (1998)
Studia Mathematica
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We define a handy new modulus for normed spaces. More precisely, given any normed space X, we define in a canonical way a function ξ:[0,1)→ ℝ which depends only on the two-dimensional subspaces of X. We show that this function is strictly increasing and convex, and that its behaviour is intimately connected with the geometry of X. In particular, ξ tells us whether or not X is uniformly smooth, uniformly convex, uniformly non-square or an inner product space.
Javier Alonso, Carlos Benítez (1989)
Extracta Mathematicae
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Yunbai Dong, Qingjin Cheng (2013)
Studia Mathematica
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Let 𝓐 be a compatible collection of bounded subsets in a normed linear space. We give a characterization of the following generalized Mazur intersection property: every closed convex set A ∈ 𝓐 is an intersection of balls.
Lin, C.-S. (1992)
International Journal of Mathematics and Mathematical Sciences
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Mohamed Akkouchi, Hassan Sadiky (1993)
Extracta Mathematicae
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R. M. Aron and R. H. Lohman introduced, in [1], the notion of lambda-property in a normed space and calculated the lambda-function for some classical normed spaces. In this paper we give some more general remarks on this lambda-property and compute the lambda-function of other normed spaces, namely: B(S,∑,X) and M(E).
Serb, Ioan (1999)
Mathematica Pannonica
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C.-S. Lin (2005)
Colloquium Mathematicae
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We first introduce a notion of (a,b,c,d)-orthogonality in a normed linear space, which is a natural generalization of the classical isosceles and Pythagorean orthogonalities, and well known α- and (α,β)-orthogonalities. Then we characterize inner product spaces in several ways, among others, in terms of one orthogonality implying another orthogonality.