This week's featured article
| A still life is a pattern that does not change from one generation to the next, and thus may be thought of as an oscillator with period 1. Still lifes are sometimes assumed to be finite and non-empty. The two main subgroups of still lifes are strict still lifes and pseudo still lifes. In some contexts, the term "still life" may refer to strict still lifes.
A strict still life is a still life that is either connected (i.e., has no islands), or is such that removing one or more its islands destroys the stability of the pattern. For example, beehive with tail is a strict still life because it is connected, and table on table is a strict still life because neither of the tables are stable by themselves.
A pseudo still life consists of two or more islands which can be partitioned (either individually or as sets) into non-interacting subpatterns which are by themselves each still lifes. Furthermore, there must be at least one dead cell that has more than three alive neighbours in the overall pattern but has less than three alive neighbours in the subpatterns. This final restriction removes patterns such as bakery, blockade and fleet from consideration, as the islands are not "almost touching".
| The LifeWiki contains one of the most comprehensive catalogues of patterns available on the internet. Within it you will find:
Did you know...
- ...that sixteen spaceship velocities have been constructed, including two infinitely adjustable families of ships?
- ...that there are 71 distinct ways for two gliders to collide, but it is unknown how many distinct 3-glider collisions there are?
- ...that the largest interesting pattern constructed, the caterpillar, contains over 11 million cells?
- ...that the Gosper glider gun was the first pattern to be discovered that exhibits infinite growth?
- ...that the block-laying switch engine and the glider-producing switch engine are the only two infinitely-growing patterns that are known to have ever occurred naturally from a random starting configuration?
- ...that oscillators are known that oscillate at all periods other than 19, 23, 34, 38 and 41?
- ...that the pentadecathlon and the blinker are the only known oscillators that are polyominos in more than one phase?
- ...that it is impossible for a period 3 oscillator to be a phoenix?
- ...that the methuselah with the longest known lifespan, 40514M, lasts for over 40,000 generations before stabilizing? The second-place holder, Fred, runs for over 35,000 ticks.
- ...that replicators with quadratic population growth are known to exist in Conway's Game of Life, but none have yet been found?