56 research outputs found
Computing Aggregate Properties of Preimages for 2D Cellular Automata
Computing properties of the set of precursors of a given configuration is a
common problem underlying many important questions about cellular automata.
Unfortunately, such computations quickly become intractable in dimension
greater than one. This paper presents an algorithm --- incremental aggregation
--- that can compute aggregate properties of the set of precursors
exponentially faster than na{\"i}ve approaches. The incremental aggregation
algorithm is demonstrated on two problems from the two-dimensional binary Game
of Life cellular automaton: precursor count distributions and higher-order mean
field theory coefficients. In both cases, incremental aggregation allows us to
obtain new results that were previously beyond reach
Direct Counting Analysis on Network Generated by Discrete Dynamics
A detail study on the In-degree Distribution (ID) of Cellular Automata is
obtained by exact enumeration. The results indicate large deviation from
multiscaling and classification according to ID are discussed. We further
augment the transfer matrix as such the distributions for more complicated
rules are obtained. Dependence of In-degree Distribution on the lattice size
have also been found for some rules including R50 and R77.Comment: 8 pages, 11 figure
Probabilistic initial value problem for cellular automaton rule 172
We consider the problem of computing a response curve for binary cellular
automata -- that is, the curve describing the dependence of the density of ones
after many iterations of the rule on the initial density of ones. We
demonstrate how this problem could be approached using rule 130 as an example.
For this rule, preimage sets of finite strings exhibit recognizable patterns,
and it is therefore possible to compute both cardinalities of preimages of
certain finite strings and probabilities of occurrence of these strings in a
configuration obtained by iterating a random initial configuration times.
Response curves can be rigorously calculated in both one- and two-dimensional
versions of CA rule 130. We also discuss a special case of totally disordered
initial configurations, that is, random configurations where the density of
ones and zeros are equal to 1/2.Comment: 13 pages, 3 figure
On Factor Universality in Symbolic Spaces
The study of factoring relations between subshifts or cellular automata is
central in symbolic dynamics. Besides, a notion of intrinsic universality for
cellular automata based on an operation of rescaling is receiving more and more
attention in the literature. In this paper, we propose to study the factoring
relation up to rescalings, and ask for the existence of universal objects for
that simulation relation. In classical simulations of a system S by a system T,
the simulation takes place on a specific subset of configurations of T
depending on S (this is the case for intrinsic universality). Our setting,
however, asks for every configurations of T to have a meaningful interpretation
in S. Despite this strong requirement, we show that there exists a cellular
automaton able to simulate any other in a large class containing arbitrarily
complex ones. We also consider the case of subshifts and, using arguments from
recursion theory, we give negative results about the existence of universal
objects in some classes
Surjective cellular automata far from the Garden of Eden
Automata, Logic and SemanticsInternational audienceOne of the first and most famous results of cellular automata theory, Moore's Garden-of-Eden theorem has been proven to hold if and only if the underlying group possesses the measure-theoretic properties suggested by von Neumann to be the obstacle to the Banach-Tarski paradox. We show that several other results from the literature, already known to characterize surjective cellular automata in dimension d, hold precisely when the Garden-of-Eden theorem does. We focus in particular on the balancedness theorem, which has been proven by Bartholdi to fail on amenable groups, and we measure the amount of such failure
- …