Life

Life is a cellular automaton on an infinite square lattice with semi-totalistic rules, designed by mathematician John Horton Conway in the 70's. In less specialized terms, Life can naively be described in term of "cells" susceptibles of two states, named Alive and Dead, on an unbounded chess-like board, with rules to be applied iteratively and simultaneously to each cell according to the number of alive cells surrounding it. Those rules endow the "Life Universe" with dramatics and worth studying behaviors. There exists many equivalent definitions, with no real best exposure despite most exotic attempts; the following is as Conway stated them in one of his rare publication on the subject:

• BIRTH. A cell that's dead at time $t$ becomes live at $t+1$ only if exactly three of its eight neighbors were live at $t$.

• DEATH by overcrowding. A cell that's live at $t$ and has four or more of its eight neighbors live at $t$ will be dead by time $t+1$.

• DEATH by exposure. A live cell that has only one live neighbor, or none at all, at time $t$, will also be dead at $t+1$.

• SURVIVAL. A cell that was live at time $t$ will remain live at $t+1$ if and only if it had just 2 or 3 live neighbors at time $t$.

Links

• Life Interlude, a page I uploaded to the internet back in 1998 that survived to this day (archived).