Algebraic invariants for crystallographic defects in cellular automata
Marcus Pivato · Ergodic Theory and Dynamical Systems · 2006
Let , and partly explain the outcomes of their collisions. Some invariants are based on the cocycles of multidimensional subshifts; others arise from the higher-dimensional (co)homology/homotopy groups for subshifts, obtained by generalizing the Conway–Lagarias tiling groups and the Geller–Propp fundamental group.