Parameters in Banach spaces and orthogonality

Year 2022, Volume: 5 Issue: 1, 37 - 45, 14.03.2022

Pier Luigi Papini Marco Barontı

https://doi.org/10.33205/cma.1067323

Abstract

In Banach spaces, plenty of parameters have been considered: they are often defined by using
pairs of vectors. Rarely, they are defined by considering pairs of vectors which are orthogonal in
the sense of Birkhoff and James; in that case the study is often not easy. In fact, it can be difficult
to identify pairs of orthogonal vectors; so to calculate the value of these parameters, to compare
them with the other parameters, to see if they have some stability with respect to changes of the
norm. In this paper, we shall do this for a couple of new parameters.

Keywords

Orthogonal vectors, James constant, uniform non squareness

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