Computation and construction universality of reversible cellular automata

An arbitrary d-dimensional cellular automaton can be constructively embedded in areversible one having d+1 dimensions. In particular, there exist computation- and construction-universal reversible cellular automata. Thus, we explicitly show a way of implementing nontrivial irreversible processes in a reversible medium. Finally, we derive new results for the bounding problem for configurations, both in general and for reversible cellular automata

Various pushing methods on grid graphs

This thesis describes algorithms for determining if a grid of switches can be turned into all-off state from any initial configuration by various methods of activation operation (push). Among these push methods, besides the regular + push, + push with no center, X push, X push with no center, and a V -typed unbalanced push are studied. The research methods used in this work are mainly linear algebra and algorithm analysis. Results obtained include that the grid m x n is completely solvable with push + no center, if and only if co-prime (m+1, n+1)

On some one-sided dynamics of cellular automata

A dynamical system consists of a space of all possible world states and a transformation of said space. Cellular automata are dynamical systems where the space is a set of one- or two-way infinite symbol sequences and the transformation is defined by a homogenous local rule. In the setting of cellular automata, the geometry of the underlying space allows one to define one-sided variants of some dynamical properties; this thesis considers some such one-sided dynamics of cellular automata. One main topic are the dynamical concepts of expansivity and that of pseudo-orbit tracing property. Expansivity is a strong form of sensitivity to the initial conditions while pseudo-orbit tracing property is a type of approximability. For cellular automata we define one-sided variants of both of these concepts. We give some examples of cellular automata with these properties and prove, for example, that right-expansive cellular automata are chain-mixing. We also show that left-sided pseudo-orbit tracing property together with right-sided expansivity imply that a cellular automaton has the pseudo-orbit tracing property. Another main topic is conjugacy. Two dynamical systems are conjugate if, in a dynamical sense, they are the same system. We show that for one-sided cellular automata conjugacy is undecidable. In fact the result is stronger and shows that the relations of being a factor or a susbsystem are undecidable, too