What life-like rules are interesting and what are not?

[David]

Formerly, the title of this topic was 'Can Life-like Celluar Automata without B2 and B3 be actually interesting?'.

Without B2 and B3 (and B1 and B0), every pattern can't escape its bounding box, and thus spaceships can't exist.

Other rules where spaceships can't exist include:
* Any rule with S0123, trailling pattern cannot die.
* Any rule with B23/S0, ditto.
* Any rule with B1, explodes to every direction.
* Any rule without one of B245/S012345, can't escape its bounding diamond.
* Any rule with S234567 and without B2, ditto.
* Any rule with S123456, connected patterns cannot shrink.
(Is there any missing criteria?)

Did anyone find any rule where spaceships can't exist actually interesting?

EDIT: I changed the topic, as codeholic claimed that opinion is different, person by person.

[codeholic]

It depends how you define interesting. Is a Turing-complete CA interesting enough?

[David]

I wanted people to base on their own opinion what is interesting and what is not.
I don't like these rules:
* B1 rules are never interesting, as they just explodes anyway. (example: Gnarl[B1/S1], H-trees[B1/S012345678]. I won't declare Replicator[B1357/S1357] and Fredkin[B1357/S02468] as not interesting, though.)
* B2 rules, even though they at least have oscillators and sometimes spaceships, as they explodes, too. (example: Seeds[B2/S], Live free or die[B2/S0], Persian rug[B234/S])
* Almost every other quickly exploding rule. (example: 34 Life[B34/S34], Life Without Death[B3/S012345678], Maze[B3/S12345])
* Slowly exploding, "expanding" rules. (example: Coral[B3/S45678], Stains[B3678/S235678], But Coagulations[B378/S235678] is an exception. I think this is beautiful...)
* Amoeba[B357/S1368] and Diamoeba[B35678/S5678]. they just swim in space.
* Longlife[B345/S5]... This is an ethernal jail.
* Any rule that doesn't have B2 and B3, because spaceships can't exist in them.
* Highlife[B36/S23] is a special case, because of its naturally occuring replicator. I parse this replicator as a dangerous object... (Sounds quite crazy, though.)

And I like these rules:
* Conway's Game of Life[B3/S23]
* 2x2[B36/S125]
* Pseudo Life[B357/S238]
* Morley[B368/S245]
* Day & Night[B3678/S34678]

I wanted to hear people's opinion, as they probably like rules I don't like, and vice versa.

[Scorbie]

I also like chaotic rules with long-lasting but non-expanding growth.

* Any rule that doesn't have B2 and B3, because spaceships can't exist in them.

If you like coagulations then I think you would also like its black/white reversal... which is b478/s234678, I think.

[dvgrn]

Here's one of the things that I find most fascinating in Conway's Life, but where I haven't really explored analogies in other rules.

There are a surprising number of cases where setting up an infinite agar in a rule effectively changes the rules of the universe. It's kind of like sound traveling at a different speed through metal, or light moving slower through glass.

For example, signals carried by B3/S23 spaceships can't travel faster than c/2 orthogonally or c/4 diagonally -- yet we have a simple wire that can carry 2c/3 signals. Or if you fill the universe full of stripes agar, you can suddenly have lightspeed bubbles, "negative spaceships" that can travel at the speed of light parallel to the stripes (in fact, they can't move slower than lightspeed)... or spaceships that travel at 2c/3 perpendicular to the stripes.

So... for these various rules that can't escape their bounding box, suppose the bounding box is infinite to begin with (because the default tile is something other than empty space). I bet that in quite a few cases, with the right choice of simple agar, things that looks suspiciously like spaceships will suddenly become possible after all.

[Kiran]

For some strange reason Stains[B3678/S235678] does not explode, but if some birth and survival are removed, it does.
Also, B2 rules can be interesting as long as patterns are engineered to not explode.
What about B0 but not S8 rules?
Those flickering rules can be very unusual if the flickering is cancelled out by using negative colours on odd generations.
Some exploding rules, such as B1/S45678, crystallize in interesting ways.

[Naszvadi]

For some strange reason Stains[B3678/S235678] does not explode, but if some birth and survival are removed, it does.
...

Stains do will explode. At least with linear growth rate. See this.

And also not just weird rules may become turing-complete after tiling with certain patterns, but also B1*/, B0*/ and B2*/ rules' exploding patterns' boundaries might contain elements for proving universality.

(Curious: why isn't allowed to publish entries in lifewiki about solving the growth problem in Stains? http://conwaylife.com/w/index.php?title=Stains )

[drc]

Stains do will explode. At least with linear growth rate. See this.

That's B235678/S3678, which is explosive. The rule wasn't specified correctly.

[Naszvadi]

Stains do will explode. At least with linear growth rate. See this.

That's B235678/S3678, which is explosive. The rule wasn't specified correctly.

... I wonder if somebody could not guess from the embedded pattern files

Thanks for the observation, anyway!

[confocaloid]

See also forum threads:
Very nearly exploding rules
Rules with interesting dynamics
Developing a more detailed classification of rule behaviors
How do you keep track of INT rules?
Why so little interest in multistate rules?