B2(B2/S)

[EvinZL]

This rule, being simple, also has many interesting points that made me think that it deserves a thread. It has 3 common spaceships(photons):

• Code: Select all

  x=2, y=4, rule=B2/S
  ob$bo$bo$ob!

• Code: Select all

  x=3, y=4, rule=B2/S
  o2b$2bo$2bo$o2b

• Code: Select all

  x=3, y=4, rule=B2/S
  bo$2bo$2bo$o!
  

A simple p2 oscillator:

Code: Select all

x=2, y=3, rule=B2/S
ob$bo!

A simple seed:

Code: Select all

x=1, y=2, rule=B2/S
o$o!

Some random puffer:

Code: Select all

x=2, y=3, rule=B2/S
o$bo$bo!

Another:

Code: Select all

x=6, y=4, rule=B2/S
obobo$obo2bo$3o2bo$3bo!

Another:

Code: Select all

x=7, y=6, rule=B2/S
4b2o$3bo$2bo3bo$bo2b2o$ob2obo$b4o!

And a puffrake:

Code: Select all

x=24, y=24, rule=B2/S
22bo$23bo$23bo$22bo$21bo$20bo$19bo$18bo$17bo$16bo$15bo$14bo$13bo$12bo$
11bo$10bo$9bo$8bo$7bo$6bo$5bo$4bo$o2bo$b2o!

[AforAmpere]

This rule is called Seeds, and already has a thread here. And here.

[dvgrn]

This rule is called Seeds, and already has a thread here. And here.

There's also a Seeds article on the LifeWiki with links to existing pattern collections and so on. That makes it fairly famous as these things go, since the LifeWiki mostly tries to stay focused on B3/S23, just to keep things from getting really horribly confusing. There's also a Seeds article on Wikipedia (!).

Also maybe worth mentioning: Genaro Juárez Martínez and others have written a number of papers about a rule they call the "Diffusion Rule", B2/S7. As far as I can tell, this rule is really just B2/S in disguise. The S7 part of the "Diffusion Rule" can only be triggered by live cells with seven live neighbors in the initial condition, and spaceships and other long-lasting patterns described in the papers don't seem to include any S7 behavior, as far as I've seen.

There's a good reason for this: you can make an infinite stable agar of seven-neighbor ON cells, but a finite area containing such cells will inevitably shrink from the edges at the speed of light, surviving (at best) a number of ticks equal to the radius of the area. After any primordial 7-neighbor ON cells have disappeared, there's no way for them to reappear, so B2/S7 emulates B2/S from then on.