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Spontaneous Emergence of Robust Cellular Replicators
Iker Azpeitia and Jesús Ibáñez
*
Computer Languages and Systems Department, University of the Basque Country.
649 Posta Kutxa, 20080 Donostia, Spain
Abstract.
An experimental method is developed to evaluate the possibility of
spontaneous emergence of self-reproducing patterns from a quasi-random
configuration. In order to achieve viability to the emerging patterns and to their
components a robust transition table is designed. Genetic reproduction is
compared with self-inspection based reproduction in order to conclude that the
latter is better adapted to achieve the specified goal.
1
Introduction
One of the first applications, if not the first, of Cellular Automata was the study of the
logic of reproduction. John von Neumann [1] regarded reproduction as the ability that
living systems exhibit to produce entities and structures as complex as themselves,
and opposed to artificial construction processes, in which there is generally a
degradation in complexity between the constructing agent and the constructed object.
Von Neumann postulated that this ability was the minimum requirement to allow the
possibility of open ended evolution, or, to use his own terminology, the possibility of
unbounded increase of complexity.
After his awesome work and that of his immediate collaborators [2,3], in which an
actual reproducing two-dimensional huge pattern was designed, several authors have
developed alternative models to achieve reproduction in simpler conditions than those
envisaged by von Neumann, the most notable of those being Chris Langton's [4].
Besides the main goal of achieving reproduction, the different cellular patterns were
intended to serve a variety of purposes: to test the role of universality [4,5], to find a
minimal model as simple as possible [6,7], to allow reproducers to perform additional
tasks [8,9,10] or to try different strategies in the reproducing process [11,12,13,14].
In all the cases the designed patterns are able to reproduce provided they are placed
in a
quiescent
cellular space and are not intended to work in an unfriendly
environment. This scenario has been proved to be appropriate to test the existence of
reproducers under different hypotheses, but not to achieve von Neumann's original
goal. If reproduction is to be the basis for any kind of evolution, it can be supposed
that variation and selection mechanisms are going to take place. The consequence of
both will be a cellular space occupied not only by struggling patterns who try to fill a
*
This work has supported in part by the Research Department of the University of the Basque
Country under grant 9/UPV 00003230-13707/2001. The authors want to acknowledge the
useful comments and suggestions made by the anonymous referees.
