Sometimes thousands of generations at a time. Remarkable speed by storing subpatterns in a hash table and using them to skip forward, HashLife is a life algorithm that achieves Two-dimensional cellular automaton games similar to life but with different rules have been constructed and given the names HexLifeĪnd HighLife. (in particular, rule 110), can be universal. More amazingly still, as shown by Wolfram (2002), even one-dimensional cellular automata Uses live cells in an area of, and can calculate approximately 20 generations It a true model of universal computation in the game of life. Machine, the values in the registers of Chapman's machine are unbounded, making Unlike the finite tape of Rendell's Turing On D. Hickerson's 'sliding block memory' approach that implements Subsequently, on November 11, 2002, P. Chapman constructed a life pattern based Simply by making his tape infinite, he neither noted this fact nor provided an actualĬonstruction of a universal Turing machine. While Rendell's machine can be made into a 'true' universal computer Machine was explicitly implemented in life by P. Rendell (Rendell, AdamatzkyĢ001). That can be extended to a universal Turing The outlines of a proof for life's universality That can be translated into a system known to be universal. The long-open 'unique father problem' of determining if a pattern exists which has a father pattern but no grandfather pattern (Wainwright 1972, Gardner 1983, p. 249), was settled by Ilkka Törmä and Ville Salo in January 2022 with the discovery of a 374-cell example of such a pattern, a result that was quickly reduced to the 306-cell pattern illustrated above (apgoucher 2022, LifeWiki).Īmazingly, life is a universal cellular automaton, in the sense that it is effectively capable of emulating any cellularĪutomaton, Turing machine, or any other system The first such pattern was not found until 1971 and many are now known (LifeWiki). Many counterexamples were subsequently found, including guns and puffer trains (illustrated above).Ī life pattern which has no father pattern is known as a Garden of Eden (for obvious biblical reasons). Patterns that cycle through a set of configurations are called oscillators.Ĭonway originally believed that no pattern could produce an infinite number of cells, and offered a $50 prize to anyone who could find a counterexample before the end of 1970 (Gardner 1983, p. 216). Several still lifes are illustrated above. Life :=Ī pattern which does not change from one generation to the next is known as a still life, and is said to have period 1. (Here, corresponds to the initial pattern.) Where the initial conditions are specifiedĪnd the results for generations through are returned. The game of life is a totalistic cellular automaton, and can be implemented as follows using the built-in command CellularAutomaton, Birth: if the current cell is off and the count is exactly 3, the current cell is switched on. Survival: if (a) the count is exactly 2, or (b) the count is exactly 3 and the current cell is on, the current cell is left unchanged.ģ. Death: if the count is less than 2 or greater than 3, the current cell is switched off.Ģ. Then used to determine what will happen to the current cell.ġ. Any cells that are on are counted, and this count is All eight of the cells surrounding the current one are checked Each generation then switchesĬells on or off depending on the state of the cells that surround it. The life cellular automaton is run by placing a number of filled cells on a two-dimensional grid. Originally played (i.e., successive generations were produced) by hand with counters,īut implementation on a computer greatly increased the ease of exploring patterns. Scientific American column starting in October 1970. The game of life is the best-known two-dimensional cellular automaton, invented by John H. Conway and popularized in Martin Gardner's

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