- For the general concept of camelships as slope 3 spaceships, see Oblique spaceship.
|View static image|
|Number of cells||239822|
|Discovered by||Chris Cain|
|Year of discovery||2018|
On December 7, 2018, Chris Cain created a self-constructing camelship spaceship, the first known spaceship with the minimum possible step size of (3,1). It was also considerably smaller than the Gemini 3, the only other known spaceship with a (3N, N) direction of travel.
The camelship's design is roughly based on a volatility-1 oscillator constructed the previous month.
The volatility-1 oscillator's two halves are rotationally symmetric, which allows it to re-use the same destruction and reconstruction recipes on both sides of its loop. By contrast, the camelship needs two separate single-channel recipes. The first recipe shoots down the circuitry on the left side and rebuilds it at an offset of (-3, -1). If this recipe were reflected 180 degrees and used to shift the right-side circuitry, it would have the effect of moving it by (3, 1) instead of (-3, -1) and the loop would no longer line up correctly.
Instead, the second recipe (which is inactive on the left side due to the first recipe constructing an eater on the construction arm lane) is activated on the right side by a glider that crosses the entire camelship on every cycle. This glider is produced by the leading gliders in the first recipe in the course of shifting a marker block by (-3, -1) near the north corner. The glider interrupts the copied recipe along the southeast side, exactly at the transition point between the first and second recipes.
So at the east corner, the first recipe is absorbed by an eater (moose antlers) and the second recipe is activated to shift the right-side circuitry by (-3, -1).
Application to other speeds
A similar method could be adapted to shift circuitry by any chosen distance, to make spaceships with other small step sizes, including oblique directions: giraffeship, ibisship, zebraship, antelopeship, etc. The recipes involving the eaters in the east and west corners and the block near the north corner would have to be re-invented or adjusted for each new step, but much of the other circuitry could remain the same. The only exception is that for any step (X, Y) where X+Y is odd, the reflecting circuitry on the right side must be different from the circuitry on the left, because the single-channel recipes in such a spaceship will travel on alternate colours in successive cycles.
- Chris Cain. Re: Self-Constructing Spaceship Challenges (discussion thread) at the ConwayLife.com forums