This week's featured article
| 2×2 is a Life-like cellular automaton in which cells survive from one generation to the next if they have 1, 2 or 5 neighbours, and are born if they have 3 or 6 neighbours. That is, it is governed by the rulestring "B36/S125". Patterns under the rule have a chaotic evolution similar to those under the standard Life rules, but the chaos tends to die out much more quickly.
The 2×2 rule gets its name from the fact that it can emulate a simpler cellular automaton that acts on each 2×2 block. The emulated automaton is a block cellular automaton that makes use of the Margolus neighbourhood. As a result, patterns that are originally made up of 2×2 blocks will forever be made up of 2×2 blocks, but the block partition will be offset by one cell in the odd generations from the even generations. There are 212 = 4096 such Life-like automata, of which 2×2 is the most well-known.
| The LifeWiki contains one of the most comprehensive catalogues of patterns available on the internet. Within it you will find:
Did you know...
- ... that the smallest known sawtooth pattern in Conway's Life consists of only 177 ON cells?
- ... that there are now over a hundred and twenty known Herschel conduits, counting stable conduits only, and a much larger number if oscillator-supported conduits are included?
- ... that Demonoids, caterloopillars, orthogonoids and half-bakery knightships are the only known types of spaceships with fixed slope but adjustable speed?
- ... that a pattern exists in which no cell in the unbounded Life plane ever becomes periodic?
- ... that several candidate universal constructors have been demonstrated in Conway’s Life, but as of June 2015 none have been formally proven to be universal?
- ... 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 prime pairs or Fermat primes?