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Durham University

Computer Science


Publication details for Dr Maximilien Gadouleau

Castillo-Ramirez, Alonso & Gadouleau, Maximilien (2020). Elementary, finite and linear vN-regular cellular automata. Information and Computation 104533.

Author(s) from Durham


Let G be a group and A a set. A cellular automaton (CA)  over AG is von Neumann regular
(vN-regular) if there exists a CA  over AG such that  =  , and in such case,  is called a
weak generalised inverse of  . In this paper, we investigate vN-regularity of various kinds of
CA. First, we establish that, over any nontrivial con guration space, there always exist CA
that are not vN-regular. Then, we obtain a partial classi cation of elementary vN-regular CA
over f0; 1gZ; in particular, we show that rules like 128 and 254 are vN-regular (and actually
generalised inverses of each other), while others, like the well-known rules 90 and 110, are
not vN-regular. Next, when A and G are both nite, we obtain a full characterisation of
vN-regular CA over AG. Finally, we study vN-regular linear CA when A = V is a vector
space over a eld F; we show that every vN-regular linear CA is invertible when V = F and
G is torsion-free elementary amenable (e.g. when G = Zd; d 2 N), and that every linear CA
is vN-regular when V is nite-dimensional and G is locally nite with char(F) - o(g) for all
g 2 G.