Birkhoff-James classification of norm's properties
Abstract
For an arbitrary normed space over a field , we define the directed graph induced by Birkhoff-James orthogonality on the projective space , and also its nonprojective counterpart . We show that, in finite-dimensional normed spaces, carries all the information about the dimension, smooth points, and norm's maximal faces. It also allows to determine whether the norm is a supremum norm or not, and thus classifies finite-dimensional abelian -algebras among other normed spaces. We further establish the necessary and sufficient conditions under which the graph of a (real or complex) Radon plane is isomorphic to the graph of the two-dimensional Hilbert space and construct examples of such nonsmooth Radon planes.
Cite
@article{arxiv.2402.13416,
title = {Birkhoff-James classification of norm's properties},
author = {Alexander Guterman and Bojan Kuzma and Sushil Singla and Svetlana Zhilina},
journal= {arXiv preprint arXiv:2402.13416},
year = {2024}
}
Comments
Accepted for publications in AOT in The Special Issue Dedicated to Professor Chi-Kwong Li