Grid designs

This paper investigates the existence of GG-designs (decompositions of complete graphs into edge-disjoint copies of a grid graph GG), proving that such designs exist for toroidal grids CnCnC_n \square C_n when nn is an odd prime or its square, and for the path-grid P4P4P_4 \square P_4 (which relates to scrambling Connections puzzles), while showing that P3P3P_3 \square P_3 admits no such design.

Alon Danai, Joshua Kou, Andy Latto, Haran Mouli, James Propp2026-03-11🔢 math