This is an announcement for the paper Strongly extreme points and approximation properties” by Trond A. Abrahamsenhttps://arxiv.org/find/math/1/au:+Abrahamsen_T/0/1/0/all/0/1, Petr Hájekhttps://arxiv.org/find/math/1/au:+Hajek_P/0/1/0/all/0/1, Olav Nygaardhttps://arxiv.org/find/math/1/au:+Nygaard_O/0/1/0/all/0/1, Stanimir Troyanskihttps://arxiv.org/find/math/1/au:+Troyanski_S/0/1/0/all/0/1.
Abstract: We show that if $x$ is a strongly extreme point of a bounded closed convex subset of a Banach space and the identity has a geometrically and topologically good enough local approximation at $x$, then $x$ is already a denting point. It turns out that such an approximation of the identity exists at any strongly extreme point of the unit ball of a Banach space with the unconditional compact approximation property. We also prove that every Banach space with a Schauder basis can be equivalently renormed to satisfy the sufficient conditions mentioned. In contrast to the above results we also construct a non-symmetric norm on $c_0$ for which all points on the unit sphere are strongly extreme, but none of these points are denting.
The paper may be downloaded from the archive by web browser from URL https://arxiv.org/abs/1705.02625