Spontaneous Near-Criticality and Type-Graded Robustness in a Four-Atom Conway Cellular Automaton

Abstract

A minimal variant of Conway's Game of Life, extended by four atom types and a 4x4 inter-type interaction matrix, spontaneously lands inside the Wilting-Priesemann near-critical band on 100/100 nominal trials across five structured presets, while a 20-random-matrix x 5-seed baseline lands in-band on only 56/100 trials (Wilson 95% CIs disjoint; pooled Cohen's d about 1.0). Under leave-one-out atom-class suppression, Cohen's d for the population drop ranges from 11.99 (critical class) to 1.67 (loss-absorbing class), a roughly sevenfold separation. A roughly 540x Lyapunov-variance amplification under any single-class suppression in the all-cooperative regime makes the spectral non-expansion property browser-visible. Life's own near-criticality is established (Reia and Kinouchi, 2014); what is added here is that the band is entered selectively, by structured presets and not by most random matrices, and that the same composition carries a type-classified robustness signature. The simulator, raw sweep, analysis script and statistics file are deposited as a separate software record.