English

Diameter 2 properties and convexity

Functional Analysis 2015-06-18 v1

Abstract

We present an equivalent midpoint locally uniformly rotund (MLUR) renorming XX of C[0,1]C[0,1] on which every weakly compact projection PP satisfies the equation IP=1+P\|I-P\| = 1+\|P\| (II is the identity operator on XX). As a consequence we obtain an MLUR space XX with the properties D2P, that every non-empty relatively weakly open subset of its unit ball BXB_X has diameter 2, and the LD2P+, that for every slice of BXB_X and every norm 1 element xx inside the slice there is another element yy inside the slice of distance as close to 2 from xx as desired. An example of an MLUR space with the D2P, the LD2P+, and with convex combinations of slices of arbitrary small diameter is also given.

Keywords

Cite

@article{arxiv.1506.05237,
  title  = {Diameter 2 properties and convexity},
  author = {Trond A. Abrahamsen and Peter Hájek and Olav Nygaard and Jarno Talponen and Stanimir Troyanski},
  journal= {arXiv preprint arXiv:1506.05237},
  year   = {2015}
}

Comments

15 pages

R2 v1 2026-06-22T09:55:04.168Z