A linear growth pattern with the apgcode
yl512_1_-10_b7fcb4a3dcd2ed771cdee759694f89f1 has shown up. This is the first yl512, as well as potentially the first negative growth pattern:
Code: Select all
x = 32, y = 32, rule = B3/S23
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For those who don't know, the -10 in the apgcode refers to it losing 10 cells every 512 generations. This is not some sort of perpetually shrinking object, rather, a quirk of the linear growth detection algorithm.
The object produced is a symmetric
ark that fires gliders back at ash, and there are two of them due to the D4 symmetry of the soup. At T=32327, a forward-facing glider that resulted from the ash collisions hits the main engine. The back-facing gliders that come out next hit the new ash, while the ones that were already produced continue to head to the origin. By that point, the central ash has already moved out of the way and all gliders that make it there are annihilated by identical, symmetrically produced gliders from the opposing ark.
I believe that this reaction happened at just the right time for a linear growth check to happen, and apgsearch saw that there was a loss of 10 cells (2 gliders) per 512 generations at the origin, because there were no new gliders being produced in the same stream. 512 isn't the period of the ark, but it is the amount of time between each glider arriving at the origin, due to the ark getting further and further away. The soup also produced a proper apgcode for another linear growth pattern in the same soup,
yl1536_1_482_d44ba9fdc6341229bec6087cb5bfd3d8, which may have been given to the other ark. 32327 is also close to a power of 2, 32768, so that might've been the time at which some important check happens.
I've attached a population plot up to T=40000. The red region is ~T=32000 and onwards. The big spike is due to the new ash reaction, but you can see some downward motion as the gliders continue to die off.
If someone that knows more about exactly how apgsearch object detection works can explain this in a better way, feel free.