English

Diameter two properties, convexity and smoothness

Functional Analysis 2016-10-11 v2

Abstract

We study smoothness and strict convexity of (the bidual) of Banach spaces in the presence of diameter 2 properties. We prove that the strong diameter 2 property prevents the bidual from being strictly convex and being smooth, and we initiate the investigation whether the same is true for the (local) diameter 2 property. We also give characterizations of the following property for a Banach space XX: "For every slice SS of BXB_X and every norm-one element xx in SS, there is a point ySy\in S in distance as close to 2 as we want." Spaces with this property are shown to have non-smooth bidual.

Keywords

Cite

@article{arxiv.1606.00221,
  title  = {Diameter two properties, convexity and smoothness},
  author = {Trond A. Abrahamsen and Vegard Lima and Olav Nygaard and Stanimir Troyanski},
  journal= {arXiv preprint arXiv:1606.00221},
  year   = {2016}
}

Comments

Removed Proposition 2.7 from version [v1] because of a gap in the proof. arXiv admin note: text overlap with arXiv:1506.05237

R2 v1 2026-06-22T14:14:47.412Z