Self%20Reproducing%20CA

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Self Reproducing CAs and Programs

• Shruti Parihar
• May 06, 2003

Computer Science Dept, San Jose State University,
CA
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Agenda

• Introduction to ALife
• Father of ALife John von Neumann
• Significance of Neumanns Discovery
• Langtons Contributions
• Loops
• Concept of Death
• Cell-Lab demo of Langtons Loops
• Viruses Self Replicating Programs
• Conclusions

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Introduction to ALife

• What is Alife?
• Extracting mechanics of evolution
• Understanding Rules of life
• Significant work done
• John von Neumann
• Chris Langton
• Others

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Father of ALife John von Neumann
Neumanns 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

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Father of ALife John von Neumann
Neumanns UTM
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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

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Contributions of Chris Langton
Langtons 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
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Contributions of Chris Langton
Loop Reproduction
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Contributions of Chris Langton
Loop Death
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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 Neumanns automata by reducing number
  of states to 8
• Automaton required 100 million cells
• John Devore
• Simplified Codds automata to occupy 94, 794 cells

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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

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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

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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
• Darwins 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?

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Conclusions and Future Scope

• Neumanns theories of Self reproduction lay
  foundations
• Langtons contributed by materializing the
  automata theory through programs allowing for
  experimentation and improvement
• Viruses are self replicating programs which dont
  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

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Questions?