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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.

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Background

This question strengthens the density inquiry by asking not only for a point between a and b, but for a whole non-degenerate subcontinuum whose points lie between a and b in the ultrafilter order.

Such a property would connect order-theoretic density with geometric structure in chainable continua, potentially revealing deeper interactions between the ultrafilter order and the continuum’s subcontinua.

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)