English

Geometric aspects of $p$-angular and skew $p$-angular distances

Functional Analysis 2021-07-23 v1

Abstract

Corresponding to the concept of pp-angular distance αp[x,y]:=xp1xyp1y\alpha_p[x,y]:=\left\lVert\lVert x\rVert^{p-1}x-\lVert y\rVert^{p-1}y\right\rVert, we first introduce the notion of skew pp-angular distance βp[x,y]:=yp1xxp1y\beta_p[x,y]:=\left\lVert \lVert y\rVert^{p-1}x-\lVert x\rVert^{p-1}y\right\rVert for non-zero elements of x,yx, y in a real normed linear space and study some of significant geometric properties of the pp-angular and the skew pp-angular distances. We then give some results comparing two different pp-angular distances with each other. Finally, we present some characterizations of inner product spaces related to the pp-angular and the skew pp-angular distances. In particular, we show that if p>1p>1 is a real number, then a real normed space X\mathcal{X} is an inner product space, if and only if for any x,yX{0}x,y\in \mathcal{X}\smallsetminus{\lbrace 0\rbrace}, it holds that αp[x,y]βp[x,y]\alpha_p[x,y]\geq\beta_p[x,y].

Keywords

Cite

@article{arxiv.1705.07039,
  title  = {Geometric aspects of $p$-angular and skew $p$-angular distances},
  author = {J. Rooin and S. Habibzadeh and M. S. Moslehian},
  journal= {arXiv preprint arXiv:1705.07039},
  year   = {2021}
}

Comments

20 pages, to appear in Tokyo J. Math

R2 v1 2026-06-22T19:52:40.830Z