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Quasiconvexity from weak (1,∞)-Poincaré inequality in Euclidean domains

Determine whether every Euclidean domain Ω ⊂ R^n that supports a weak (1,∞)-Poincaré inequality with respect to the Lebesgue measure restricted to Ω is quasiconvex.

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Background

This question arises after establishing that, under a doubling assumption, a weak (1,∞)-Poincaré inequality implies (very) ∞-thick quasiconvexity. The authors wonder whether the doubling assumption can be removed when working in Euclidean domains with the Lebesgue measure, and formalize this uncertainty into a precise question.

A positive answer would provide a self-improvement path from local analytical control (weak (1,∞)-Poincaré inequality) to geometric connectivity (quasiconvexity) in domains without assuming a doubling property for the restricted measure.

References

Related to \Cref{prop:quasiconvexity_2}, it is not clear to us if we can dispense with the doubling assumption on $Z$. We formulate the problem as the following special case.

If a domain $\Omega\subsetRn$ supports a $(1,\infty)$-weak Poincaré inequality, does it follow that $\Omega$ is quasiconvex?

Infinity thick quasiconvexity and applications (2509.01194 - García-Bravo et al., 1 Sep 2025) in Question (ques:PI), Section 3.3