The rhombic dodecahedral conjecture asserts that a regular rhombic dodecahedron has the least surface area among three-dimensional parallelohedra of a fixed inradius. Cesaroni and Novaga (2026) proved the sharp inequality
where
is the surface area and
is the inradius. Equality
holds iff
is similar to a regular rhombic
dodecahedron. This is a fixed-inradius problem,
distinct from minimizing surface area at fixed volume.
Cesaroni and Novaga (2026) report using ChatGPT to check algebraic identities and explore proof arguments. The authors checked the final statements and proofs.