Transfinite almost square Banach spaces
Volume 271 / 2023
Studia Mathematica 271 (2023), 39-63
MSC: Primary 46B20; Secondary 46B03, 46B04, 46B26.
DOI: 10.4064/sm220517-4-11
Published online: 12 January 2023
Abstract
Is is known that a Banach space contains an isomorphic copy of $c_0$ if, and only if, it can be equivalently renormed to be almost square. We introduce and study transfinite versions of almost square Banach spaces with the purpose of relating them to the containment of isomorphic copies of $c_0(\kappa )$, where $\kappa $ is some uncountable cardinal. We also provide several examples and stability results for the above properties by taking direct sums, tensor products and ultraproducts. By connecting the above properties with transfinite analogues of the strong diameter 2 property and octahedral norms, we obtain a solution to an open question of Ciaci et al. [Israel J. Math. (online, 2022)].
