Information Technology Reference
In-Depth Information
The formation through the natural selection;
The obvious uncertainty of behavior.
The above really facilitates understanding what makes a life body unique.
The key problem is self-reproduction, which is not only the most important
characteristic of the naturally generated organisms, but also the most important
characteristic to distinguish the life and non-life bodies. However, not all the
natural life bodies are capable of reproducing themselves, so it is still considered
that the boundaries of life exist. For example, the prions contain the protein, but
not the ribonucleic acid. Take the AIDS retroviruses as another example, which
contain RNA, but not DNA. They can not reproduce themselves, but replace the
metabolic system of the host. The relation between the definitions of
reproduction and life is not clear. For example, mules and castrated persons can
walk, talk, and think, but not reproduce themselves, which shows they are alive
by all the standards. Therefore, reproduction is not the defined characteristic of
life.
The fundamental theories of artificial life research include the cellular
automata theory, morphogenesis theory, chaos theory, genetic theory,
information complexity theory, etc. In the following sections, the introductions
will be given respectively.
15.5 Cellular Automata
Cellular automata (CA) provide another example of recursively applying a
simple set of rules to a structure. In a CA, the structure that is being updated is
the entire lattice of finite-automata. In this case, the local rule set is the transition
function obeyed homogeneously by every automaton in the lattice. The local
context considered in updating the state of each automaton is the state of the
automata in its neighborhood. The transition function of automata constructs a
kind of local physical components in a simple, discrete space/time universe. The
universe is updated by applying the local physics to each “cell” of its structure
again and again. Although the physical structure itself does not develop in this
process, its state does.
In such universes, all processing methods can be embedded to propagate
information in the universe meaningfully, depending on the rule
context-sensitivity of local neighborhood conditions. In particular, the general
purpose computers can be embedded. Since these computers are simply
