Half-distance separator by a two-dimensional manifold in R^3
Determine whether, for any two disjoint continua A,B ⊂ R^3 (in particular, for disjoint simply connected continua), there exists a compact connected two-dimensional manifold C ⊂ R^3 such that A and B lie in different components of R^3 \ C and the Euclidean distance satisfies ρ(C, A ∪ B) = ρ(A,B)/2.
References
So the question of the validity of the ``topological'' analog of Corollary~\ref{corr.razdelenie.rho/2} remains open: Let ${A},{B}\subseteq$ be two disjoint (simply connected) continua. Is there a (compact, connected) two-dimensional manifold ${C}$ such that ${A}$ and ${B}$ lie in different components of $\setminus{C}$ and $\rho({C},{A}\cup{B})=\rho({A},{B})/2$ ?
— Separation of plane sets by equidistant simple closed curves
(2403.20166 - Volkov et al., 29 Mar 2024) in Question (ques.r3), Section “Similar questions in R^3”