Kakeya set with high Turing join
Construct a Kakeya set A in R-squared such that the Turing join of the coordinates of every point in A computes the halting problem.
References
Is there a Kakeya set $A\subseteq\mathbb{R}2$ such that $x\oplus y\geq_T\emptyset'$ for every $(x,y)\in A$?
— Open Problems in Mathematical Logic
(2608.26628 - Barmpalias et al., 27 Aug 2026) in Section 4