Classical Borsuk partition problem in dimensions four through sixty-three
Determine whether every bounded subset of R^d can be partitioned into d+1 subsets of strictly smaller Euclidean diameter for dimensions 4≤d≤63.
References
Today, there are known counterexamples in dimensions $64$ and higher, see , but the problem is still open for $4\leq d\leq 63$.
— On Lattice Diameter Segments and A Discrete Borsuk Partition Problem
(2508.20009 - Brose et al., 27 Aug 2025) in Introduction, paragraph discussing Borsuk's partition problem