gameoflifemaniac wrote:Is there a pattern other than the dot, domino or other symmetric patterns that can't be a spaceship in any non-totalistic rule?

Presuming that your question is about isotropic non-totalistic rules, then calcyman answered this question conclusively, and in the affirmative, here. There was some further discussion around the topic (restricted to isotropic rules without B0) in that thread as well.

muzik wrote:Any pattern can be a spaceship in some non-isotropic rules, which are non-totalistic.

I'm pretty sure gameoflifemaniac is referring to isotropic, non-totalistic rules, where the dot and domino cannot be a spaceship.

Saka wrote:muzik wrote:Any pattern can be a spaceship in some non-isotropic rules, which are non-totalistic.

Not sure about that. What about this:Code: Select all`x = 93, y = 81, rule = B/S01234678`

76bo$76bo55$o24$91b2o!

That pattern is certainly a spaceship in some non-isotropic, non-totalistic rule - so it doesn't serve as a counter example to muzik's statement. Even if you restrict consideration to isotropic rules, I don't think you can simply rule out that it might be a spaceship in some rule. For example, here is a pattern made of two isolated dominos which is a spaceship in an isotropic rule with B0:

Code: Select all

`x = 5, y = 5, rule = B02c3e6e/S1e`

4bo$4bo3$2o!

It seems it would be extremely unlikely for the two domino + dot pattern to be a spaceship in some isotropic rule, but I don't think you can rule it out without a proof or actually testing a large majority of the B0 rules which support spaceships (some of them you'd be able to rule out without testing explicitly, I'm sure).

By the way, Thank you to the people who contributed to discussion of this topic in the other thread (who hopefully read this thread too!), and apologies for not participating in the discussion. I've still got lots of thoughts about this which I'm trying to straighten out in my head.

Edit:

Here's another example with larger spacing:

Code: Select all

`x = 6, y = 6, rule = B02c3ry4qtwz6e/S02an4r5r6n`

5bo$5bo4$2o!

And another without the diagonal symmetry:

Code: Select all

`x = 5, y = 6, rule = B01e2-a3j4ay5ac6ai8/S1c4k`

4bo$4bo4$2o!