For any dimension n >= 3, we establish the corner poset, a natural triangular poset structure on the corners of 2-color hypercubes. We use this poset to study a problem motivated by a classical cube stacking puzzle posed by Percy MacMahon as well as Eric Cross's more recent "Eight Blocks to Madness." We say that a hypercube is 2-color when each of its facets has one of two colors. Given an arbitrary multiset of 2-color unit n-dimensional hypercubes, we investigate when it is possible to find a submultiset of 2(n) hypercubes that can be arranged into a larger hypercube of side length 2 with monochrome facets. Through a careful analysis of the poset and its properties, we construct interesting puzzles, find and enumerate solutions, and study the maximum size, S(n), for a puzzle that does not contain a solution. Further, we find bounds on S(n), showing that it grows as Theta(n2(n)).
Title
The corner poset with an application to an n-dimensional hypercube stacking puzzle
Berkove, E. and J. Shettler (2022) "The corner poset with an application to an n-dimensional hypercube stacking puzzle." Australasian Journal of Combinatorics 84 (1): 86-110.