Subcontinuum bridging property between two points in ultrafilter order
Determine whether, for every chainable continuum X, every ultrafilter order ≤_U^D on X, and any two distinct points a,b ∈ X, there exists a non-degenerate subcontinuum K ⊆ X such that for all x ∈ K one has a ≤_U^D x ≤_U^D b.
References
We state here some open questions. We also ask the following stronger question. Is it true that for every chainable continuum X, every ultrafilter order \leq_{\U}{\D} on X and any two distinct points a,b \in X there exists a non-degenerate subcontinuum K\subseteq X such that for all x\in K we have: a \leq_{\U}{\D} x \leq_{\U}{\D} b?
                — Linear orders on chainable continua
                
                (2510.14577 - Marciszewski et al., 16 Oct 2025) in Section 7 (Questions)