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 mirrored 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".
In the news
- January 24: Charity Engine discovers a strictly volatile period-25 oscillator, Charity's p25.
- January 23: Keith Amling discovers a period-8 c/2 greystretcher component that uses blocks to stabilize the zebra stripes.
- January 20: Darren Li uses Open Science Grid and a modified ikpx2 to find a surprisingly small (2,1)c/6 tagalong, which can be attached to Sir Robin, Sir Sprayer, and various minstrels in a wide variety of ways, including a connection to itself.
- January 20: Matthias Merzenich completes a gliderless lightweight spaceship gun based on a partial result by iNoMed and Christopher D'Agostino.
- January 17-19: Carson Cheng and iNoMed discover small glider guns for periods 70, 72, and 84.
- January 12: Adam P. Goucher discovers the walrus, the first known elementary c/8 diagonal spaceship.
- January 2-8: Rocknlol reduces the minimum population record for a Max predecessor to 110 cells. Rocknlol subsequently reduces this by finding a 107-cell Max predecessor, as well as a predecessor fitting in a record 21×19 bounding box.
|The LifeWiki contains one of the most comprehensive catalogues of patterns available on the internet. Within it you will find:
Did you know...
- ... that there are dozens of known Cordership variants, including puffers, rakes and wickstretchers, with periods of any multiple of 96?
- ... that greyships have been constructed with speeds of c/2, c/3, c/4, c/5, and 2c/5?
- ... that most greyships travel parallel to the stripes in their included agars, but a few travel perpendicular to the stripes, or "against the grain"?
- ... that a pattern has been constructed that calculates and prints out the digits of pi in decimal, and a similar one prints out the decimal digits of the Golden Ratio?
- ... that several different patterns have been constructed to calculate and display the sequence of prime numbers, and some have been adapted to display only twin primes or Fermat primes?
- ... that two completely different types of oblique spaceships, the waterbear and the half-baked knightship, were constructed in 2014?
- ... that no Caterpillar-type spaceships were completed for almost ten years after the original Caterpillar was constructed in 2004, but that two different designs, the waterbear and the centipede, were finished in 2014?
- ... that the first spiral-growth pattern in Conway's Life was constructed in 2014?
- ... that among known glider recipes for irreducible objects, the Gemini spaceship has the largest known minimal recipe not counting encoded RCT recipes, currently 173,449 gliders — the runner-up being the self-synthesizing oblique loopship which is its own 144,221-glider synthesis?
- ... that it was shown in 2014 that any salvo of gliders, no matter how tightly packed, can be constructed by crashing together gliders whose initial positions are farther apart than any chosen finite distance?