Computer Science Dept, San Jose State University, CA Self Reproducing CA’s and Programs Shruti Parihar May 06, 2003

AgendaAgenda 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 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 Neumann’s Automata

Father of ALife – John von Neumann Neumann’s UTM

Contributions of Chris Langton 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 Loops

Contributions of Chris Langton Langton’s Loop 0 – Background cell state3, 5, 6 – Phases of reproduction 1 – Core cell state4 – 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?Questions?