8 papers
A natural class of cellular automata containing fractional multiplication automata, Rule 30, and others
Johan Kopra
We define the class of rapidly left expansive cellular automata, which contains fractional multiplication automata, Wolfram's Rule 30, and many others. The definition has been shap…
Sofically presented dynamical systems
Johan Kopra, Ville Salo
Systems obtained by quotienting a subshift of finite type (SFT) by another SFT are called finitely presented in the literature. Analogously, if a sofic shift is quotiented by a sof…
Direct Prime Subshifts and Canonical Covers
Johan Kopra
We present a new sufficient criterion to prove that a non-sofic half-synchronized subshift is direct prime. The criterion is based on conjugacy invariant properties of Fischer grap…
On the Trace Subshifts of Fractional Multiplication Automata
Johan Kopra
We address the dynamics of the cellular automaton (CA) that multiplies by in base (for coprime ) by studying its trace subshift. We present a conjugacy of the tra…
Glider automata on all transitive sofic shifts
Johan Kopra
For any infinite transitive sofic shift we construct a reversible cellular automaton (i.e. an automorphism of the shift ) which breaks any given finite point of the subshift…
Dynamics of cellular automata on beta-shifts and direct topological factorizations
Johan Kopra
We consider the range of possible dynamics of cellular automata (CA) on two-sided beta-shifts . We show that any reversible CA has an almost equicontinuous dire…