GUYTU6J wrote: ↑February 13th, 2020, 8:10 am

Synthesise_patt_v1.2.py cannot replace the central glider pair with 3G. Does either of the 2G-to-G reflection work?

I think glider kickbacks are pretty hopeless for this kind of thing, but let's go ahead and do the tests. Kickbacks are confusing, but they're not exactly rocket surgery. Here are the two kickback reactions from two-glider-syntheses.rle:

Code: Select all

```
x = 33, y = 21, rule = LifeHistory
13.2D$14.2D$13.D2$30.3D$32.D$31.D$7.A$6.A20.A$6.3A17.A$26.3A7$23.A$.
2A19.2A$A.A19.A.A$2.A!
```

When the green gliders collide, they'll end up in the red marked locations in 60 ticks. So all you have to do is rewind three of the gliders in the invalid 4G collision -- i.e., move each of the gliders backwards by 60 ticks, which is 15 cells diagonally -- and then drop in one of these recipes in the place of the remaining glider (so the red marked cells cover up the glider).

Here's a test page that could be used to try all sixteen combinations of kickback and orientation:

Code: Select all

```
x = 339, y = 766, rule = LifeHistory
134.A129.A$133.A129.A$133.3A127.3A13$119.D129.D$118.D129.D$118.3D127.
3D19$108.A$10.2D98.2E128.2D$10.D.D97.E.E127.D.D$10.D99.E129.D.A2$16.A
92.3D127.3E77.3D$14.A.A94.D129.E79.D$15.2A93.D129.E79.D2$25.A310.3D$
23.2A313.D$24.2A311.D$113.3D127.3D$113.D129.D68.A.A18.A$114.D129.D67.
2A18.A$313.A18.3A$255.2A$255.A.A$6.2D247.A$6.D.D$6.D87.3A$96.A$95.A
233.A$307.2A19.2A$308.2A18.A.A$14.A292.A$15.2A$14.2A112.3A127.3A$128.
A129.A$129.A129.A$25.A$24.2A$24.A.A32$134.A129.A$133.A129.A$133.3A
127.3A13$119.D129.D$118.D129.D$118.3D127.3D19$108.A$110.2E128.2D$110.
E.E127.D.D$110.E129.D.A2$109.3D127.3E$111.D129.E$110.D129.E5$113.3D
127.3D$113.D129.D$114.D129.D2$255.2A$255.A.A$255.A2$94.3A$96.A$95.A5$
128.3A127.3A$128.A129.A$129.A129.A35$134.A129.A$133.A129.A$133.3A127.
3A13$119.D129.D$118.D129.D$118.3D127.3D19$108.A$110.2E128.2D$110.E.E
127.D.D$110.E129.D.A2$109.3D127.3E$111.D129.E$110.D129.E5$113.3D127.
3D$113.D129.D$114.D129.D2$255.2A$255.A.A$255.A2$94.3A$96.A$95.A5$128.
3A127.3A$128.A129.A$129.A129.A35$134.A129.A$133.A129.A$133.3A127.3A
13$119.D129.D$118.D129.D$118.3D127.3D19$108.A$110.2E128.2D$110.E.E
127.D.D$110.E129.D.A2$109.3D127.3E$111.D129.E$110.D129.E5$113.3D127.
3D$113.D129.D$114.D129.D2$255.2A$255.A.A$255.A2$94.3A$96.A$95.A5$128.
3A127.3A$128.A129.A$129.A129.A35$134.A129.A$133.A129.A$133.3A127.3A
13$119.D129.D$118.D129.D$118.3D127.3D16$17.2D$17.D.D$17.D$108.A$2D
108.2E128.2D$D.D107.E.E127.D.D$D109.E129.D.A2$109.3D127.3E77.3D$25.A
85.D129.E79.D$6.A19.2A82.D129.E79.D$4.A.A18.2A$5.2A307.A$313.A$313.3A
$113.3D127.3D$113.D129.D$114.D129.D60.A.A$9.2A19.A275.2A$8.2E2A17.2A
224.2A49.A$8.EAE18.A.A223.A.A$255.A2$94.3A$96.A$95.A227.3D$325.D$324.
D3$128.3A127.3A$128.A129.A$129.A129.A$314.A.A$314.2A$315.A2$305.2A$
306.2A$305.A28$134.A129.A$133.A129.A$133.3A127.3A13$119.D129.D$118.D
129.D$118.3D127.3D19$108.A$110.2E128.2D$110.E.E127.D.D$110.E129.D.A2$
109.3D127.3E$111.D129.E$110.D129.E5$113.3D127.3D$113.D129.D$114.D129.
D2$255.2A$255.A.A$255.A2$94.3A$96.A$95.A5$128.3A127.3A$128.A129.A$
129.A129.A35$134.A129.A$133.A129.A$133.3A127.3A13$119.D129.D$118.D
129.D$118.3D127.3D19$108.A$110.2E128.2D$110.E.E127.D.D$110.E129.D.A2$
109.3D127.3E$111.D129.E$110.D129.E5$113.3D127.3D$113.D129.D$114.D129.
D2$255.2A$255.A.A$255.A2$94.3A$96.A$95.A5$128.3A127.3A$128.A129.A$
129.A129.A35$134.A129.A$133.A129.A$133.3A127.3A13$119.D129.D$118.D
129.D$118.3D127.3D19$108.A$110.2E128.2D$110.E.E127.D.D$110.E129.D.A2$
109.3D127.3E$111.D129.E$110.D129.E5$113.3D127.3D$113.D129.D$114.D129.
D2$255.2A$255.A.A$255.A2$94.3A$96.A$95.A5$128.3A127.3A$128.A129.A$
129.A129.A!
```

There's a third set of adjustments, though. To have any chance of success, the kickback has to happen at the last possible moment. So let's take the upper left corner case in the test page:

Code: Select all

```
x = 130, y = 69, rule = LifeHistory
128.A$127.A$127.3A13$113.D$112.D$112.3D19$102.A$4.2D98.2E$4.D.D97.E.E
$4.D99.E2$10.A92.3D$8.A.A94.D$9.2A93.D2$19.A$17.2A$18.2A$107.3D$107.D
$108.D4$2D$D.D$D87.3A$90.A$89.A3$8.A$9.2A$8.2A112.3A$122.A$123.A$19.A
$18.2A$18.A.A!
```

Drop one of the red gliders in one of the groups of three on the left, directly on top of the yellow sabotaged glider, and you'll end up with five gliders that would make that invalid 4G collision -- if the gliders didn't interact too soon:

Code: Select all

```
x = 42, y = 66, rule = LifeHistory
40.A$39.A$39.3A13$25.D$24.D$24.3D19$14.A$16.2D$16.D.D$16.D2$15.3D4.A$
17.D2.A.A$16.D4.2A2$31.A$29.2A$30.2A$19.3D$19.D$20.D6$3A$2.A$.A5$34.
3A$34.A$35.A!
```

So we want to make the kicked-back glider appear at the last possible minute. It turns out that we can delay the kickback recipe gliders in time by multiples of 4 -- i.e., move them each two steps diagonally backwards -- and then move both gliders in whatever direction is "forwards" from the point of view of the kicked-back glider. This is the part I find a little confusing: I have to mumble things to myself, like "

*Okay, I moved both gliders backward, so now they're going to get where they're going ***too late**, so to make up for that by moving the location where they're going to collide, by the same distance."

In this case the final result is that one glider moves by (-2N, -2N) and the other moves by (0,-2N):

Code: Select all

```
x = 42, y = 66, rule = LifeHistory
40.A$39.A$39.3A13$25.D$24.D$24.3D19$14.A$16.2D$16.D.D$16.D3.A$18.A.A$
15.3D.2A.B$17.D2.B.B$16.D4.2B8.A$29.2A$30.2A$29.2B$30.2B$19.3D$19.D$
20.D6$3A$2.A$.A5$34.3A$34.A$35.A!
```

Keep moving the gliders until just before the kickback doesn't work any more, and you'll find out that... even the last-possible-moment kickback still doesn't work:

Code: Select all

```
x = 42, y = 66, rule = LifeHistory
40.A$39.A$39.3A13$25.D$24.D$24.3D10$8.A$6.A.A$7.2A2$31.A$29.2A$30.2A
4$16.2D$16.D.D$16.D2$15.3D4.B$17.D2.B.B$16.D4.2B2$31.B$29.2B$30.2B$
19.3D$19.D$20.D6$3A$2.A$.A5$34.3A$34.A$35.A!
```

Trying the other fifteen possibilities would probably be good practice for working with kickbacks. But I think the kickback reaction will always get mixed up with the other glider somehow.