Is every spaceship in OCA a glider?

[Haycat2009]

This thread is meant for discussion about whether every spaceship in OCA is a glider, since it propagated into the “glider loop” thread.

Please voice your opinions (especially if you think that there is only 1 glider or want to point out a mid ground), this is the thread for them.

I would love to move the relevant posts here, but I do not have the moderator’s crowbar™ to move posts.

The point:
There is only one glider, 5P4H1V1, a polyplet in a 3x3 box. Please post here if you beg to differ.

Well, these are not gliders. If one part is incorrect, can we even verify that they count in this discussion?

[confocaloid]

Some relevant previous discussion

Here's a fun middle ground that calls back to the etymology:

A glider is any small, natural, glide-reflective spaceship in a rule. Small spaceships that don't flip around during their motion period, like a hat ship or the like, aren't gliders.

From the intuitiveness viewpoint, I agree with the part "small, natural". Personally, I'm likely to use the word 'glider' for small common gliders. And I'm likely to use the word 'spaceship' for large spaceships (beyond loafer in CGoL, possibly including the loafer as well).

However, some will say that waterbear and Sir Robin are gliders too.

I certainly disagree with "glide-reflective". LeapLife has an oblique glider (lepa). 11life has an orthogonal c/11 glider. There is a glider on an aperiodic tiling: https://aperiodical.com/2012/08/a-glide ... on-exists/

There are many sources describing spaceships as gliders, regardless of their symmetry. Those sources cannot be ignored.

I appear to be outnumbered. From Discord: Mecejide, PlanetN9ne, and AlbertArmStain say those are not gliders. EvinZL says they are.

Hmm. Outnumbered on Discord, anyway.

However, there are quite a number of authoritative sources that will tell you that it's perfectly okay to call those various things "gliders" -- in the right context.

See, in particular, David Eppstein's now-offline collection entitled "Gliders in Life-Like Cellular Automata" -- still called "GliderDB" in the latest incarnation ... because "glider" has very regularly been used as a general term for things that move in cellular automata -- basically a synonym for "spaceship".

"Glider" isn't used much for Conway's Life spaceships; when we're talking about Life, we say "spaceship" for everything except CGoL gliders, and "glider" for CGoL gliders.

But in my experience, moving things in non-CGoL patterns can validly be called "gliders", and patterns that make them shuttle back and forth can validly be called "glider shuttles".

1. OCA can have gliders.

Yes, as Gliders are not endemic, but these are not gliders.

Surely they are. Various people described them as gliders.
Further reading: https://www.google.com/search?q=gliders ... r+automata

1. OCA can have gliders.

2. Stable 180° reflectors can be part of a shuttle. Periodic vs. stable has absolutely nothing to do with it. (I'm not taking a side on the word "loop".)

Well, these are not gliders. If one part is incorrect, can we even verify that they count in this discussion?

Those are definitely gliders. Just not the diagonal c/4 gliders from Life. And obviously various people described them as gliders in the quoted posts.
[...]

Here is an old example of an alien glider shuttle-

[...]
ETA²: Sparky glider shuttle.

Code: Select all

x = 28, y = 25, rule = sansdomino_s13
12bo4$12bo2$6bo3bo3bo3bo2$12bo2$21b2o3b2o$23bo$12bo8b2o3b2o4$2o3b2o5bo
$4bo7bo$2o3b2o6bo2$15bo$15bo$13b2ob2o$15bo$15bo!

Code: Select all

x = 28, y = 25, rule = B2-a/S13
12bo4$12bo2$6bo3bo3bo3bo2$12bo2$21b2o3b2o$23bo$12bo8b2o3b2o4$2o3b2o5bo
$4bo7bo$2o3b2o6bo2$15bo$15bo$13b2ob2o$15bo$15bo!

Other examples (incomplete):

p168 glider shuttle:

Code: Select all

x = 34, y = 35, rule = crawl
20bo$19bobo$19b2o$14b3ob2o$16bob2o$17bo12bo$29b3o$28b2o2bo$29b5o$31b3o
10$13bo$11b2o$12b2o$9bo$10bo2$3o$5o$bo2b2o$2b3o$3bo12bo$14b2obo$14b2ob
3o$13b2o$12bobo$13bo!

[...]
Glider shuttle:

Code: Select all

x = 27, y = 24, rule = B2e3/S23-jq
9b3o$10bo$10bo2$8bo3bo$7bo5bo2$5bo$4bo21bo$o24bo$3o7b2o9bo$o11bo8b3o$
4bo5b2o9bo$5bo19bo$26bo4$13b3o$14bo$14bo2$12bo3bo$11bo5bo!

[...]

p32 glider shuttle and 'juggler':

Code: Select all

x = 112, y = 53, rule = B2e3aceij5-ijr/S23-a4
26bo58bo$25b3o56b3o$25bobo56bobo4$20b2o9b2o46b2o9b2o$21bo9bo48bo9bo$
21b2o3bo3b2o48b2o3bo3b2o$22bob2ob2obo50bob2ob2obo$21b2obo3bob2o48b2obo
3bob2o$21bo2bo3bo2bo48bo2bo3bo2bo$20b2o2bo3bo2b2o46b2o2bo3bo2b2o$24b2o
b2o54b2ob2o$26bo58bo6$6bo5bo27bo5bo18bo5bo27bo5bo$6b3ob3o27b3ob3o18b3o
b3o27b3ob3o$8b3o31b3o22b3o31b3o2$9b5o25b5o24b5o11b2o12b5o$b2o6bo3bo25b
o3bo6b2o8b2o6bo3bo11b3o11bo3bo6b2o$2o6bo5bo23bo5bo6b2o6b2o6bo5bo12b2o
9bo5bo6b2o$b2o6bo3bo25bo3bo6b2o8b2o6bo3bo13b2o10bo3bo6b2o$9b5o25b5o24b
5o25b5o2$8b3o19b3o9b3o22b3o19b3o9b3o$6b3ob3o17bo9b3ob3o18b3ob3o17bo9b
3ob3o$6bo5bo17bo9bo5bo18bo5bo17bo9bo5bo6$26bo58bo$24b2ob2o54b2ob2o$20b
2o2bo3bo2b2o46b2o2bo3bo2b2o$21bo2bo3bo2bo48bo2bo3bo2bo$21b2obo3bob2o
48b2obo3bob2o$22bob2ob2obo50bob2ob2obo$21b2o3bo3b2o48b2o3bo3b2o$21bo9b
o48bo9bo$20b2o9b2o46b2o9b2o4$25bobo56bobo$25b3o56b3o$26bo58bo!

[...]

[...]
This allows now for ridiculously small oscillators of period p29+4N (2gliders shuttle, with population 14!) and p31+4N (1 glider shuttle):

Code: Select all

x = 68, y = 37, rule = B2ci3ai4c8/S02ae3eijkq4iz5ar6i7e
4$21bo21bo$15bo3bo16bo4bo$19b2o20b2o$8bo13bo6bo14bo2$9bobo4bo13bobo4bo
2$8bo13bo6bo14bo$19b2o20b2o$15bo3bo16bo4bo$21bo21bo11$11bo8bo26bo10bo
2$4bo22bo12bo24bo2$5bobo4bo6bo4bobo14bobo4bo8bo4bobo2$4bo22bo12bo24bo
2$11bo8bo26bo10bo!

[...]

Is this 17-cell p708 glider shuttle known?

Code: Select all

x = 65, y = 74, rule = B2-a/S12
63bo$63bo4$61bo$64bo$59bobo2bo46$18bo$19b2o12$4bo$4bo4$2bo$5bo$obo2bo!

I guess these posts provide some additional evidence, that various people preferred the word 'shuttle', when they talked about glider shuttles in actual non-meta discussions about CA patterns. Which probably means the word was a natural choice.