OCA:DryLife

DryLife
DryLife rule
Rulestring	23/37 B37/S23
Rule integer	6280
Character	Explosive
Black/white reversal	B0123478/S0234678

DryLife is a Life-like cellular automaton in which cells survive from one generation to the next if they have 2 or 3 neighbours, and are born if they have 3 or 7 neighbours.

Patterns

x = 21, y = 13, rule = B37/S23 8bo3bo$7bobobobo$8b2ob2o$b2o15b2o$o2bo13bo2bo$b3o13b3o2$b3o13b3o$o2bo 13bo2bo$b2o15b2o$8b2ob2o$7bobobobo$8bo3bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]]

The flower garden (click above to open LifeViewer)
RLE: here Plaintext: here

DryLife is so named because the standard spaceships from normal life; lightweight spaceship, middleweight spaceship, and heavyweight spaceship — also known as "fishes" — do not work, though the glider does. Some other spaceships, such as the x66, weekender and loafer, work in this rule. The copperhead evolves into the closely related c/10 goldenhead, differing from copperhead by two cells in one phase.

Two correctly spaced B-heptominoes (as in the twin bees shuttle) act as a c/2 orthogonal puffer.

A new speed allowed by DryLife is 9c/28 orthogonal. Technology travelling at this speed relies on the R-pentomino. There is a small 9c/28 orthogonal pond puffer, and a 9c/28 spaceship. Guns and breeders have been constructed that fire spaceships and rakes of this speed respectively.

The "flower garden", a common constellation composed of two bi-boats and two cis-mirrored R-bees which evolves from honey farm predecessors, is shown to the right.

Universality

There is a proof sketch of DryLife's universality on ConwayLife.com forums. It is a proof-scheme covering all rules in the outer-totalistic rulespace between B3/S23 and B3678/S23678.

In 2018, Peter Naszvadi constructed an explicit Rule 110 unit cell in DryLife, proving its Turing-completeness. The pattern itself is basically a meta-polyglot, covering some related cellular automata in which the pattern only differs in some parts (in this case, the guns).

External links

• DryLife at David Eppstein's Glider Database
• DryLife at Adam P. Goucher's Catagolue

• Puffer with unstable trail (B37/S23) (discussion thread) at the ConwayLife.com forums

• Taming B37/S23 (discussion thread) at the ConwayLife.com forums