Asymptotic geometry and Delta-points

被引:8
作者
Abrahamsen, Trond A. [1 ]
Lima, Vegard [2 ]
Martiny, Andre [1 ]
Perreau, Yoel [3 ]
机构
[1] Univ Agder, Dept Math, Postboks 422, N-4604 Kristiansand, Norway
[2] Univ Agder, Dept Engn Sci, Postboks 509, N-4898 Grimstad, Norway
[3] Univ Bourgogne Franche Comte, Lab Math Besancon, CNRS UMR 6623, 16 Route Gray, F-25030 Besancon, France
关键词
Delta-point; Daugavet-point; Asymptotic uniform smoothness; Asymptotic uniform convexity; Uniformly non-square norm; BANACH-SPACES; PROPERTY M; DAUGAVET; CONVEXITY; JAMES;
D O I
10.1007/s43037-022-00210-9
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
We study Daugavet- and Delta-points in Banach spaces. A norm one element x is a Daugavet-point (respectively, a Delta-point) if in every slice of the unit ball (respectively, in every slice of the unit ball containing x) you can find another element of distance as close to 2 from x as desired. In this paper, we look for criteria and properties ensuring that a norm one element is not a Daugavet- or Delta-point. We show that asymptotically uniformly smooth spaces and reflexive asymptotically uniformly convex spaces do not contain Delta-points. We also show that the same conclusion holds true for the James tree space as well as for its predual. Finally, we prove that there exists a superreflexive Banach space with a Daugavet- or A-point provided there exists such a space satisfying a weaker condition.
引用
收藏
页数:33
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