Self Reproducing CA’s and
Programs
Shruti Parihar
May 06, 2003
Computer Science Dept, San Jose State University, CA
Agenda
 Introduction to ALife
 Father of ALife – John von Neumann
 Significance of Neumann’s Discovery
 Langton’s Contributions
 Loops
 Concept
of Death
 Cell-Lab demo of Langton’s Loops
 Viruses : Self Replicating Programs
 Conclusions
Introduction to ALife
 What is Alife?
 Extracting
mechanics of evolution
 Understanding “Rules of life”
 Significant work done
 John
von Neumann
 Chris Langton
 Others
Father of ALife – John von Neumann
Neumann’s Automata
 Assumptions
 Computation
universality
 Construction universality
 Characteristics
 29
states, 2D Cellular automata
 Environment of infinite resources
 Self Reproduction into identical copy
 Input tape with data and instructions
 Evolution explained as well
 Significance – precursor to DNA discovery
Father of ALife – John von Neumann
Neumann’s UTM
Contributions of Chris Langton
Loops
 Assumptions
 Computation
universality not required
 Characteristics
8
states, 2D Cellular automata
 Needed CA grid of 100 cells
 Self Reproduction into identical copy
 Input tape with data and instructions
 Concept of Death
 Significance – Could be modeled through computer
programs
Contributions of Chris Langton
Langton’s Loop
0 – Background cell state
3, 5, 6 – Phases of reproduction
1 – Core cell state
4 – Turning arm left by 90 degrees
2 – Sheath cell state
state
7 – Arm extending forward cell state
Contributions of Chris Langton
Loop Reproduction
Contributions of Chris Langton
Loop Death
Other Contributions
 Dyson
 Resource
utilization of self-replicators
 Holland
 Invented
Genetic Algorithms (GA) in 1973
 Tried to imitate mechanics of evolution by applying genetic
operators
 E.F. Codd
 Simplified
Neumann’s automata by reducing number of
states to 8
 Automaton required 100 million cells
 John Devore
 Simplified
Codd’s automata to occupy 94, 794 cells
Viruses: Self Replicating Programs
 Virus is Latin for Poison
 Computer virus vs Biological virus
 Both
viruses attack a larger host entity
 Host entity turns into a factory reproducing more viruses
 Spread to other hosts
 John Inglis defines “virus” as a piece of code with two
characteristics
 At
least a partially automated capability to reproduce
 A method of transfer which is dependent on its ability to
attach itself to other computer entities like programs, disk
sectors etc
Viruses: A form of Artificial Life?
 Life is a pattern of events in time and space
 Virus
algorithms are a pattern in time
 Electric and magnetic pulses in space
 Self Reproduction
 Replication
in viruses in host entity
 Metabolism - converting matter from environment to
energy
 Consumption
of electric energy of computer system for
sustenance
 Metabolism by virus or computer?
 Metabolism in other Self Replicating Systems
Viruses: A form of Artificial Life?
 Information storage representing the living organism
 DNA strands
in living organisms
 Data and instructions on input tape (Neumann and Langton)
 Viruses use themselves as data
 Ability to grow and evolve
 Darwin’s
Evolution Theory
 Evolution in Viruses?
 Stability under environmental perturbations
 Living
organisms survive harsh weather, natural calamities
 Viruses “adapt” to changes in host system
 Attribute stability to virus or programmer?
Conclusions and Future Scope
 Neumann’s theories of Self reproduction lay foundations
 Langton’s contributed by materializing the automata theory
through programs allowing for experimentation and
improvement
 Viruses are self replicating programs which don’t quite
qualify as a form of artificial life
 Future of Self Replicating systems holds promise
 NASA proposes
Lunar factories
 Self reproducing robots are not too far ahead
Questions?