# OCA:Star Wars

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Star Wars | |

View static image | |

Rulestring | 345/2/4 B2/S345/C4 B2/S345/G4 |
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Character | Explosive |

**Star Wars**, also known as **MirekGro**, is a Generations rule devised by Mirek Wójtowicz in March 1999. In this rule, a state-0 cell will become state 1 iff it has two state-1 neighbours. A state-1 cell does not change if it has 3, 4 or 5 state-1 neighbours, otherwise it will enter state 2 next tick and then state 3 before dying.

Named after its behaviour that resembles deep space battle scenes, the rule can be described as follows:

“ | StarWars is also an interesting rule from the low-investment standpoint. In particular, it is notable for the abundance, intricacy, and variety of its naturally-occurring glider guns. In general when running "au naturel" StarWars is active to a degree almost reminiscent of Brain, with the distinction that it likes to build fixed lego-like skeletal structures. In some orbits this latter penchant reaches its zenith, and we get large universe-spanning "shells" possessing an intricate radiate geometry. | ” |

— John Elliott |

A collection of patterns in Star Wars rule is in Mirek's Cellebration. The rule can also run in modern simulators (e.g. Golly and LifeViewer) that support Generations rules.

## Patterns

### Still lifes

Still lives of population 5, 8, 10, 12 and above exists. The only 5-cell still life is the X-pentomino, or **cross**, which is a common extendable segment in larger still lives.

A group of still lives in the shape of rectangular boxes are invincible from inside, limiting the evolution similar to a finite plane; for a *m*×*n* plane the exterior has a bounding box of (*m*+4)×(*n*+4). An example with *m*=*n*=16 is shown above at lower-right corner.

### Oscillators

Due to the two dying states, oscillators of period 2 and 3 are impossible.

Many oscillators consist of one or more lightspeed signals, with a leading state-1 cell each, that are running on the surface of the stator. These oscillators are referred to as **railroads** because they look like trains running on railways. The mechanism provides at least one specimen for every period *p* ≥ 4. Specifically, jointing *q* copies of the X-pentomino orthogonally will give a still life with circumference 6*q*+6 cells (which has exactly one state-1 cell each in their Moore neighbourhoods). If 6*q*+6 = *kp* for some integer *k*, then *k* copies of the signal can be put in the circumference evenly to yield a period-*p* oscillator. The period-7 example is constructed accordingly.

### Spaceships

Most of the spaceships in Star Wars are at c orthogonal, thus are also referred to as photons.
The structure is extensible to various degrees. On March 21, 2021, Rocknlol discovered a c/6 diagonal elementary spaceship ^{[1]} which Dets65 found to be extensible ^{[2]}.

### Linear growth patterns

Guns (or rather, lasers) firing the smallest photon exist at all periods above 4, which can be constructed by connecting two still lives to the aforementioned adjustable oscillator.

Usually, abundant linear growth patterns including guns, puffers, rakes, wickstretchers and wavestretchers emerge from sufficiently large soups.

### Signal circuits

Technologies based on the smallest photon have been extensively developed. For instance, shooting the photon at the edge of a still life can split it into two lightspeed signals, which travel on the edge and merge into a photon elsewhere, or are turned into other signals. A small portion of photon conduits is shown above.

Further constructions are possible, for instance an adder^{[3]} and a Rule 110 emulator.^{[4]}

### Miscellaneous

The domino in this rule expands in a diamond shape, while the block grows quadratically generating wickstretchers.

## References

- ↑ Rocknlol (March 21, 2021). Re: Star Wars Rule (discussion thread) at the ConwayLife.com forums
- ↑ Dets65 (March 24, 2021). Re: Star Wars Rule (discussion thread) at the ConwayLife.com forums
- ↑ Jeremy Tan (March 22, 2015). An Amsterdam Adder (discussion thread) at the ConwayLife.com forums
- ↑ FWKnightship (November 18, 2020). Re: Star Wars Rule (discussion thread) at the ConwayLife.com forums

## External links

- Star Wars Rule (discussion thread) at the ConwayLife.com forums
- Star Wars at Adam P. Goucher's Catagolue
- MCell built-in Generations rules: Star Wars at Mirek Wójtowicz's Cellebration page
- Adam P. Goucher (March 7, 2014). "Emergence".
*Complex Projective 4-Space*. An article describing the emergence of structures from random soups in Star Wars.