Cardinality of order intervals in linear lattices and of their sets of extreme points
Volume 174 / 2023
Colloquium Mathematicum 174 (2023), 203-215
MSC: 06F20, 46A40, 46B42, 46E05, 52A07, 06E99.
DOI: 10.4064/cm9072-10-2023
Published online: 17 November 2023
Abstract
We characterize pairs $\mathfrak {n}$, $\mathfrak {m}$ of cardinals with the property that there exist an Archimedean linear lattice $X$ and an order interval in $X$ such that $\mathfrak {n}$ is its cardinality while $\mathfrak {m}$ is the cardinality of the set of its extreme points. We also present analogous results, complete or partial, in the case where $X$ is additionally required to be nonatomic, atomic, Dedekind $\sigma $-complete, hyper-Archimedean, or to be a $C(K)$-space, where $K$ is a compact space.