Ones explored so far include:
B2c3a/S* (Rules where B2c3a are the only birth conditions. When looking at using only the minimal birth conditions needed for spaceships, this is seemingly the hardest one to find spaceships in.)
B*-(012a)/S (Non-B0 sublight speed rules without survival conditions. All spaceships have to be phoenixes, that can't keep their fronts alive by moving at light speed.)
B2ce/S* (Similar to B2c3a in concept, but considerably more active, and some basic rules have simple spaceships. However, adding just a few extra restrictions can make this one tough, with a lot of interest in removing INT rules contained within S012)
The original intro to this thread:
This thread is for the rule space of INT rules that have only B2c3a as their birth rules (and nothing else) and have arbitrary survival rules, which has gotten some attention on the Discord lately. Inspired by a desire to prove that in non-B0 INT rules the set of B1c, B1e, B2a, B2ce, B2c3a, B2e3i, and B3ai are not just required for expanding patterns, but sufficient as sole birth rules if all survival rules are game. It turned out that B2c3a/S* is somewhat difficult to find mobile patterns in, making the ones that exist anywhere in the space of interest. Oscillators to a lesser degree can also be constrained by this and can be intriguing as well.
Early discoveries in B2c3a/S*:
Here is a document of many of the discoveries of mobile patterns made so far. Feel free to download a local copy if you wish.
https://docs.google.com/document/d/1HUQ ... sp=sharing
Some highlights:
Small c/5 spaceship found by AforAmpereorthogonal wickstretcher found by meCode: Select all
x = 8, y = 9, rule = B2c3a/S1c2a3-cj4aejnryz5-aiq6-c78 4bo2$4bo$ob4obo2$ob4obo$4bo2$4bo!c/8d spaceship found by RabbitCode: Select all
x = 8, y = 7, rule = B2c3a/S1c2ai3-cj4aejnryz5-inq6-ci78 2o4b2o$b2o2b2o$8o2$8o$b2o2b2o$2o4b2o!thick diagonal wickstretcher found by RabbitCode: Select all
x = 7, y = 7, rule = B2c3a/S3-j4aejnw5-i678 2bo2b2o$3b4o$ob4o$3b3o$4bobo2$4bo!spacefiller found by meCode: Select all
x = 9, y = 9, rule = B2c3a/S3-j4aejnw5-i678 2ob2o$5o$b3o$5o$2ob4o$4b4o$4b5o$5b2o$6bo!dynamic quadratic growth pattern found by meCode: Select all
x = 13, y = 13, rule = B2c3a/S2cn3acin4acq5acejn6-i78 obobo3bobobo$b3o5b3o$4o5b4o$b4o3b4o$o2b2o3b2o2bo$5bobo$6bo$5bobo$o2b2o 3b2o2bo$b4o3b4o$4o5b4o$b3o5b3o$obobo3bobobo!wobbling c/12 spaceship found by AforAmpereCode: Select all
x = 13, y = 7, rule = B2c3a/S2cn3acin4aq5acejn6-i78 obobo3bobobo$b3o5b3o$4o5b4o$b4o3b4o$o2b2o3b2o2bo$5bobo$6bo!Some questions for B2c3a/S*:Code: Select all
x = 6, y = 7, rule = B2c3a/S2ck3ijn4knty5-ckry6ace78 bo$b2o$4o$b4o$ob4o$3bo$bobo!
Are there puffers?
Are there guns or rakes?
Are there waves that can be stabilized?
Can you go faster than c/5? What speeds exist generally?
Is there an oblique spaceship, or growth pattern more broadly?
How many distinct speed/direction combos (as in, either can be different, not necessarily both) can be in a single rule?
Is there in general a quadratic growth pattern that grows cells of both parities as it goes? (to be precise with technicalities, a pattern where you can group cells into a rectangular tessellation such that the number of rectangles containing cells of both parities grows quadratically)