**CMU Artificial Intelligence Repository**

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## Implementations of Conway's Game of Life

areas/alife/systems/life/
aaalife/ AAALife: Fast implementation of Conway's Game of
Life for PCs.
dionne/ Life in VMS Fortran for VT100 terminals.
dr_life/ DR Life: Implementation of Conway's Game of Life
for PCs.
hatch/ Implementation of Conway's Game of Life for Sun.
hensel/ PCLIFE: Implementation of Conway's Game of Life
for the PC.
life_3d/ Life3D: Three-dimensional implementation of Life
for the Amiga.
lifepas/ Conway's Game of Life in Pascal for the PC.
moraes/ Xlife: X-Windows Implementation of Conway's Game
of Life
olsson/ Conway's Game of Life for the IBM PC
reilly/ Conway's Game of Life for Windows 3.0.
rokicki/ Conway's Game of Life for the Amiga
rupley/ Conway's Game of Life for VT100 using
curses/termcap.
xlife/ XLIFE: Conway's Game of Life for X Windows
Origin:
life.anu.edu.au:/pub/complex_systems/alife/life/
(Only some of the files come from the above site.)

This directory contains a large collection of implementations of
Conway's Game of Life for Unix, IBM PC, Amiga, and other systems.
Cellular Automata, of which Life is an example, were suggested by
Stanislaw Ulam in the 1940s, and first formalized by von Neumann.
Conway's "Game of Life" was popularized in Martin Gardner's
mathematical games column in the October 1970 and February 1971 issues
of Scientific American. (Shorter notes on life are also given in the
column in each month from October 1970 to April 1971, and well as
November 1971, January 1972, and December 1972.) There's also quite a
bit on the game in "The Recursive Universe", by William Poundstone,
Oxford University Press, 1987, 252 pages.
The rules for the game of life are quite simple. The game board is a
rectangular cell array, with each cell either empty or filled. At each
tick of the clock, we generate the next generation by the following rules:
if a cell is empty, fill it if 3 of its neighbors are filled
(otherwise leave it empty)
if a cell is filled, it
dies of loneliness if it has 1 or fewer neighbors
continues to live if it has 2 or 3 neighbors
dies of overcrowding if it has more than 3 neighbors
Neighbors include the cells on the diagonals. Some implementations use
a torus-based array (edges joined top-to-bottom and left-to-right) for
computing neighbors.
For example, a row of 3 filled cells will become a column of 3 filled
cells in the next generation. The R pentomino is an interesting
pattern:
xx
xx
x
Try it with other patterns of 5 cells initially occupied. If you
record the ages of cells, and map the ages to colors, you can get a
variety of beautiful images.
When implementing Life, be sure to maintain separate arrays for the
old and new generation. Updating the array in place will not work
correctly. Another optimization to to maintain a list of the cells
that changed.
Conway has demonstrated that it is possible to construct the basic
building blocks of a computer from Life using modified glider guns.
See the last chapter of
Elwyn R. Berlekamp, John H. Conway, and Richard K. Guy, "Winning
Ways", Academic Press, New York, 1982, ISBN 0-120911-507.
for details.
Some interesting patterns to use include:
*
* * ** * *
** * ** * * * *
** *** * * ****
* **** *** *** * *
* ** *
Clock Glider Block Spaceship * * *
* ****
*
Traffic Light Cheshire Cat

CD-ROM: Prime Time Freeware for AI, Issue 1-1
Keywords:
Artificial Life, Conway's Game of Life, Life!Implementations

Last Web update on Mon Feb 13 10:20:03 1995

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