Quasi-static equilibrium of magic squares
Peyman Fahimi · Journal of Combinatorial Mathematics and Combinatorial Computing · 2025
We model each 4\(\mathrm{\times}\)4 magic square by encoding its 16 integers as magnitudes of repelling positive point charges on a fixed 2D lattice, evolved under Coulomb forces with linear damping and a harmonic pinning to anchor sites. We simulate all 880 magic squares and compare them with equally sized ensembles of random permutations of \(\{1,{\dots},16\}\). Three readouts differentiate the ensembles. (i) Final positions: magic cases form sixteen tight, index-specific clusters on an annulus, whereas random cases show broader arcs and central accumulation. (ii) Displacement–correlation structure: across cases, many pair-of-pairs of inter-index displacements in magic squares are near-linearly dependent; the random ensemble exhibits only moderate relationships, with |r| and R\(^2\) distributions shifted to weaker correlation. (iii) Center potential: the Coulomb-type potential at the geometric center collapses to a single value at the anchors for all magic squares and remains narrowly distributed after dynamics, while random squares remain broad. Sensitivity analysis reveals a broad damping–stiffness region with high convergence, indicating that the results are robust to parameter choice.