Glider synthesis

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x = 34, y = 31, rule = B3/S23 33bo$31b2o$32b2o$9bo$bo8bo$2bo5b3o$3o3$5bo$6bo$4b3o$24bobo$25b2o$25bo 2$27bobo$27b2o$28bo$31b3o$31bo$32bo7$5b2o$6b2o$5bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ HEIGHT 600 WIDTH 600 THUMBSIZE 2 ZOOM 14 GPS 10 THEME Book AUTOSTART T 0 PAUSE 2 T 99 PAUSE 1 LOOP 100 ]]
An 8-glider synthesis of a loafer
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Glider synthesis (or glider construction) is the construction of an object by means of collisions of gliders and glider-constructible spaceships. It is generally assumed that the gliders should be arranged so that they could come from infinity - that is, gliders should not have had to pass through one another to achieve the initial arrangement (or else it is considered “not fully functional”). LWSSes, MWSSes and HWSSes can also be used in syntheses; these spaceships can themselves be easily synthesized from gliders at any point along their trajectory, so this conversion is often left as an implicit step.

Features of syntheses

Four main characterizing features of a synthesis are the geometry, construction time, glider cost, and number of stages.

The geometry is the number of directions of incoming gliders:

  • four-directional: gliders collide from all four directions
  • three-directional: gliders collide from all directions but one
  • two-directional; further divisible in head-on and 90° syntheses. All two-glider syntheses are necessarily two-directional.
  • unidirectional, which assumes the initial presence of a target (usually a still life or an oscillator) to be hit with gliders. Such syntheses are also known as slow or synchronized salvo syntheses.

Since gliders are themselves glider-constructible, any multidirectional synthesis can be technically downgraded to a fewer-directional one, usually at the cost of increasing the construction time, cost, and/or number of stages needed for the synthesis. More challenging is finding a two- or three-directional synthesis for a particular object where few or no parts of the synthesis reactions extend outside the final pattern's bounding box in a particular direction. This is especially important for the synthesis of temporary bait objects, which will need to be placed sometimes quite close to other components without perturbing them. For especially tight locations, sometimes it will be useful to construct an LWSS (or another standard c/2 spaceship) some distance away from the synthesis nexus and let that collide with a glider in the final stages; this allows synthesis at a 45° angle, rather than a 90° angle as required for synthesis by gliders from separate directions.

The construction time is simply the number of generations it takes to complete a synthesis. For multi-stage syntheses, each stage has its own construction time.

The number of stages is a count of how many separate operations a synthesis can be divided into, with pauses of arbitrary length between the stages. Often a particular synthesis operation cannot be achieved by a direct collision of gliders, and a synthesis procedure instead requires first synthesizing a number of bait objects, and then hitting these with gliders to produce the final result.

The cost is the number of gliders expended over the course of the synthesis. Similar to the construction time, it can be defined also for individual synthesis stages. A *WSS is considered to cost 3 gliders. The discovery of the reverse caber tosser in 2018 proved that there is a universal constant upper bound on the cost to synthesise any synthesisable object; currently, the best known upper bound is 15 gliders.

Of particular interest is slow salvo synthesis: unidirectional synthesis where every stage has a glider cost of one. Perhaps surprisingly, anything that is glider synthesizable is also slow salvo synthesizable, a result that crucially depends on the existence of universal construction arms as well as one-time turners and splitters.

An incremental synthesis is a synthesis with multiple stages. The final step (final stage, activation step/stage) of an incremental synthesis is the step that converts a previously constructed stationary object or constellation into the target object. Finding the final step of a synthesis is often a nontrivial, complicated process.[1][2] After the final step may come one or more cleanup steps to remove stray objects that are not part of the intended target.

Still life syntheses

In the 1990s, glider syntheses for all still lifes and known oscillators with at most 14 cells were found by David Buckingham. Almost all of these were successfully reduced to a synthesis cost of less than 1 glider per ON cell, or "1 glider per bit".[3]

A collaborative effort ending in May 2014 completed glider syntheses of all still lifes with 17 or fewer cells.[4][5][6] Lengthy projects to complete syntheses for all still lifes up to specific populations were completed for 18 bits in October 2019,[7] 19 bits in February 2020,[8] 20 bits in March 2021,[9] 21 bits in November 2022,[10] and 22 bits in August 2024.[11] Later optimization projects reduced the maximum cost of construction for 15-bit,[12][13] 16-bit,[14][15] and 17-bit[16] still lifes to less than one glider per bit, in November 2016, May 2017, and September 2019 respectively.

In September 2020, the 17-glider reverse caber-tosser proved that all synthesizable still lifes could theoretically be constructed with no more than one glider per bit.[17]

The following table displays statistics about the costs (excluding RCT constructions) for strict and pseudo still lifes with up to 21 cells as of November 15, 2022.[18]

Live cells Strict still lifes Pseudo still lifes Quasi still lifes
Count
(OEISicon light 11px.pngA019473)
Min. cost Avg. cost Max. cost Count
(OEISicon light 11px.pngA056613)
Min. cost Max. cost Count
(OEISicon light 11px.pngA330283)
Min. cost Max. cost
4 2 2 2.500 3 0 0
5 1 2 2.000 2 0 0
6 5 2 3.200 4 0 0
7 4 2 2.750 4 0 0
8 9 2 3.556 4 1 2 2 6 3 4
9 10 3 4.000 5 1 3 3 13 3 4
10 25 4 4.360 5 7 3 5 57 3 ?
11 46 4 4.543 5 16 3 6 141 3 ?
12 121 4 4.983 7 55 3 9 465 3 ?
13 240 4 5.383 8 110 4 9 1,224 3 ?
14 619 3 5.975 9 279 3 10 3,956 3 ?
15 1,353 4 6.823 10 620 4 12 11,599 4 ?
16 3,286 3 7.755 13 1,645 4 16[n 1][n 2] 36,538 3 ?
17 7,773 4 9.015 15 4,067 4 18[n 1][n 3] 107,415 3 ?
18 19,044 4 10.339 24[n 1][n 4] 10,843 4 29[n 1][n 5] 327,250 3 ?
19 45,759 4 11.632 46[n 1][n 6] 27,250 4 31[n 1][n 7] 972,040 3 ?
20 112,243 4 13.066 70[n 1][n 8] 70,637 4 40[n 1][n 9] 2,957,488 4 ?
21 273,188 5 14.734 96[n 1][n 10] 179,011 [n 11] 8,879,327 3 ?
22 672,172 4 16.604 158[n 1][n 12] 462,086 26,943,317 ? ?

In January 2022, work by Ilkka Törmä and Ville Salo demonstrated a still life with 306 cells that is impossible to synthesize with gliders, reduced by 400spartans to 278 on September 4, 2023, 236 on March 12, 2024 and 184 on September 1, 2024, meaning there is a threshold 22 < p ≤ 184 such that not all still lifes with ≥ p cells are constructible. The lower bound can be improved with a relaxing of the condition: no self-forcing patch exists within 8 × 8, so a still life would require at least 32 cells to contain one.[19]

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 15 gliders using the reverse caber-tosser
  2. All but 2 16-bit pseudo still lifes can be constructed with strictly less than one glider per bit as of September 1, 2024.
  3. All but 2 17-bit pseudo still lifes can be constructed with strictly less than one glider per bit as of September 1, 2024.
  4. All but 84 18-bit strict still lifes can be constructed with strictly less than one glider per bit as of September 1, 2024.
  5. All but 33 18-bit pseudo still lifes can be constructed with strictly less than one glider per bit as of September 1, 2024.
  6. All but 1054 19-bit strict still lifes can be constructed with strictly less than one glider per bit as of September 1, 2024.
  7. All but 51 19-bit pseudo still lifes can be constructed with strictly less than one glider per bit as of September 1, 2024.
  8. All but 5527 20-bit strict still lifes can be constructed with strictly less than one glider per bit as of September 1, 2024.
  9. All but 258 20-bit pseudo still lifes can be constructed with strictly less than one glider per bit as of September 1, 2024.
  10. All but 22,035 21-bit strict still lifes can be constructed with strictly less than one glider per bit as of September 1, 2024.
  11. Only 82941 of 179011 21-bit pseudo still lifes are currently tabulated on Catagolue.
  12. All but 86,237 22-bit strict still lifes can be constructed with strictly less than one glider per bit as of September 1, 2024.

Oscillator syntheses

The following is a table of the smallest oscillators with synthesis statistics:

Min. population Period-2 oscillators Period-3 oscillators Period-4 oscillators
Count
(OEISicon light 11px.pngA056614)
Min. cost Max. cost Count Min. cost Max. cost Count Min. cost Max. cost
3 1 2 2 0 - - 0 - -
6 3 3 4 0 - - 0 - -
8 1 4 4 0 - - 0 - -
9 1 5 5 0 - - 0 - -
10 1 5 5 0 - - 0 - -
11 1 8 8 0 - - 0 - -
12 6 5 7 1 5 5 2 5 5
13 3 5 11 1 5 5 0 - -
14 20 5 30 1 6 6 0 - -
15 29 5 14 0 - - 0 - -
16 98 4 56 7 5 8 0 - -
17 199 7(?) Incomplete 8 5 13 0 - -
18 484 4(?) Incomplete 39 5 12 3 ? ?
19 1083 ? Incomplete 66 ? ? 7 ? ?
20 2722 ? Incomplete 213 ? ? 23 ? ?
21 6596 ? Incomplete 420 ? ? 34 ? ?
Min. population Period-5 oscillators Period-6 oscillators Higher periods
Count Min. cost Max. cost Count Min. cost Max. cost Count Min. cost Max. cost
12 0 - - 0 - - 2 3 4
15 1 9 9 0 - - 1 5 5
16 1 5 5 1 5 5 1 5 5
17 2 ? ? 0 - - ? - -
18 4 ? ? 4 ? ? ? - -
19 8 ? ? 0 - - ? - -
20 16 ? ? 11 ? ? ? - -
21 42 ? ? 15 ? ? ? - -

Spaceship syntheses

Perhaps the most interesting glider syntheses are those of spaceships, because these can be used to create corresponding guns and rakes. Many of the c/2 spaceships that are based on standard spaceships have been synthesized, mostly by Mark Niemiec. In June 1998, Stephen Silver found syntheses for some of the Corderships (although it was not until July 1999 that Jason Summers used this to build a Cordership gun). Many larger Corderships also have known glider syntheses, and others could easily be generated using the same techniques. In general, larger Corderships have declined in importance after the discovery of four-, three- and two-engine versions.

In May 2000, Noam Elkies suggested that 60P5H2V0, a 2c/5 spaceship found by Tim Coe in May 1996, might be a candidate for glider synthesis. Initial attempts to construct a synthesis for this spaceship got fairly close, but it was only in March 2003 that Summers and Elkies managed to find a way to perform the crucial last step. Summers then used the new synthesis to build a c/2 forward rake for the 2c/5 spaceship; this was the first example in Life of a rake which fires spaceships that travel in the same direction as the rake but more slowly.

After the loafer was discovered and synthesized in 2013, a number of new spaceship syntheses were found during a short period of time in late 2014 and early 2015, including the dart, crab, 25P3H1V0.2, 30P5H2V0, x66, and weekender. Most of this was due to the work of Martin Grant.

Current research is ongoing for one-sided spaceship synthesis of XWSS. This allows for easier construction of convoys and flotillas, which are important components of helices, in turn important in several classes of engineered spaceships.

Name Speed First synthesis Best current synthesis
Date Discoverer Fewest gliders
60P5H2V0 2c/5 orthogonal 2003-03-17 Noam Elkies 37
loafer c/7 orthogonal 2013-02-17 Adam P. Goucher 8
dart c/3 orthogonal 2014-12-02 Ivan Fomichev, Mark Niemiec, Martin Grant, Michael Simkin 24
crab c/4 diagonal 2014-12-26 Brett Berger, Martin Grant, Tanner Jacobi 14
Parallel HBK (6,3)c/245912 2014-12-31 Michael Simkin 38,380
30P5H2V0 2c/5 orthogonal 2015-01-01 Martin Grant, Matthias Merzenich, Tanner Jacobi 39
25P3H1V0.1 c/3 orthogonal 2015-01-06 Martin Grant 19
x66 c/2 orthogonal 2015-01-11 Martin Grant, Tanner Jacobi 12
weekender 2c/7 orthogonal 2015-01-25 Chris Cain, Martin Grant, Tanner Jacobi 28
pufferfish spaceship c/2 orthogonal 2015-02-11 Chris Cain 51
Gemini (2560,512)c/16849793 2015-02-16 Dave Greene 173,449
Semi-x66 c/2 orthogonal 2015-03-08 Adam P. Goucher, praosylen, Chris Cain, Matthias Merzenich 9
B29 c/4 diagonal 2015-04-06 Tanner Jacobi 25
Pushalong 1 c/2 orthogonal 2015-06-12 Martin Grant 14
30P4H2V0 c/2 orthogonal 2015-09-10 Tanner Jacobi 50
0hd Demonoid 65c/438852 diagonal 2015-12-06 Chris Cain 12,016
copperhead c/10 orthogonal 2016-03-05 Tanner Jacobi 13
fireship c/10 orthogonal 2016-03-21 Nico Brown, Tanner Jacobi 18
25P3H1V0.2 c/3 orthogonal 2017-12-15 Martin Grant 23
Orthogonoid 16c/217251 orthogonal 2017-12-30 Dave Greene 37,625
2-engine Cordership c/12 diagonal 2017-12-31 Dave Greene 9
46P4H1V0 c/4 orthogonal 2019-02-04 Martin Grant, Tanner Jacobi 46
spider c/5 orthogonal 2019-03-07 Martin Grant 205
camelship (3,1)c/3948264 2019-05-04 Dave Greene 26,614
wings c/4 diagonal 2019-10-28 Goldtiger997, Tanner Jacobi 31
orthogonal loopship 1000130c/20003511 orthogonal 2020-01-08 Dave Greene 56,643
56P6H1V0 c/6 orthogonal 2020-03-25 AforAmpere, praosylen, Goldtiger997, Martin Grant, Tanner Jacobi 272
58P5H1V1 c/5 diagonal 2020-04-03 Adam P. Goucher, BlinkerSpawn, Goldtiger997, Peter Naszvadi, Tanner Jacobi 100
31P8H4V0 c/2 orthogonal 2020-04-10 Goldtiger997 36
70P2H1V0.1 c/2 orthogonal 2020-07-18 Martin Grant 178
44P5H2V0 2c/5 orthogonal 2020-08-29 Goldtiger997 24
55P9H3V0 c/3 orthogonal 2020-09-19 Goldtiger997 230
Speed Demonoid 1642811c/8246964 diagonal 2020-09-26 Dave Greene 31,822
57P5H2V0 2c/5 orthogonal 2020-11-02 Goldtiger997 112
turtle c/3 orthogonal 2020-12-04 Goldtiger997 225
doo-dah 2c/7 orthogonal 2020-12-06 Goldtiger997 34
edge-repair spaceship 1 c/3 orthogonal 2021-01-24 bubblegum, goldenratio 17
72P4H1V0[20] c/4 orthogonal 2021-03-08 Tanner Jacobi, Goldtiger997 194
61P4H1V0[21] c/4 orthogonal 2021-04-10 Goldtiger997 89
Canada Grey c/2 orthogonal 2021-07-01 Goldtiger997, Martin Grant 427
self-synthesizing oblique loopship (16461006,16460963)c/75568091 2021-08-02 Goldtiger997 144,221
Orion 2 c/4 diagonal 2022-01-10 Goldtiger997 57
33P4H1V1 c/4 diagonal 2022-01-14 Goldtiger997, Mark Niemiec[22] 44
70P5H2V0 2c/5 orthogonal 2022-01-26 Goldtiger997 221
58P8H4V0 c/2 orthogonal 2022-02-25 Goldtiger997, Mark Niemiec 47
SSGRL 15492980c/72085603 orthogonal 2022-03-08 Goldtiger997 141,617
30P3H1V0 c/3 orthogonal 2022-06-16 Goldtiger997 24
29P3H1V0 c/3 orthogonal 2022-06-29 Goldtiger997 35
brain c/3 orthogonal 2022-11-25 Goldtiger997 99
Infinite families of waltz stabilisations c/3 orthogonal 2022-12-09 Goldtiger997,[23] Connor Steppie[24] ≥28
66P5H2V0 2c/5 orthogonal 2022-12-23 Goldtiger997 57
37P4H1V1.1 c/4 diagonal 2022-12-28 Goldtiger997 68
77P6H1V1 c/6 diagonal 2024-01-28 Goldtiger997 222

As of June 2023, the smallest spaceships with no known syntheses are as follows:

Other syntheses of note

A 3-glider synthesis of a pentadecathlon.

A 3-glider synthesis of a pentadecathlon was found in April 1997 by Heinrich Koenig, which came as a surprise because it was widely assumed that such a small synthesis would already be known.

Along similar lines, a 3-glider synthesis of the bi-pond was discovered in June 2014 by Bob Shemyakin[25], a 3-glider synthesis of a messy glider-producing switch engine was found in October 2014 by Michael Simkin[26], and a 3-glider synthesis of a clean switch engine was discovered in March 2017 by Luka Okanishi.[27]

On March 27, 2022, dani found that two copies of Simkin's GPSE synthesis could be combined to produce a record-breaking 6-glider synthesis[28] of a breeder which had been discovered a week earlier.[29]

2-glider syntheses

Main article: 2-glider collision

There are 71 distinct 2-glider collisions, of which 28 produce nothing, six produce a block, five produce a honey farm, three produce a B-heptomino, three produce a pi-heptomino, three produce a blinker, three produce a traffic light, two produce a glider, two produce a pond, two produce a loaf and a blinker, one produces a boat, one produces a beehive, one produces a loaf, one produces an eater 1, one produces lumps of muck, one produces a teardrop, one produces an interchange, one produces a traffic light and a glider, one produces an octomino, one produces a bi-block, one produces four blocks, one produces two blocks, one produces a blinker, loaf, tub and block, and one produces the so-called two-glider mess, a methuselah stabilizing after 530 generations and consisting of four gliders, eight blinkers (including a traffic light), four blocks, a beehive and a ship.

All 71 such syntheses can be seen below in a pattern put together by Jason Summers on January 29, 2005:

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o203bo$60bo201b2o$262bobo17$67bo$66bo$4bo6bobo5bo4bobobo37b3o157bobobo 2bobobo4bo4bobo4bobo4bobo5bobo3bobo$251bo13bo13bo17bo$4bo5bo3bo3bobo3b o203bo4bo7bobo3bo6bo3bo2bo6bo3bo2bo20bo$251bo13bo13bo16b3o$4bo5bo3bo2b o3bo2bobobo199bo4bobobo2bo3bo2bobo4bo3bo2bobo4bo3bo2bobo2$4bo5bo3bo2bo bobo2bo203bo4bo6bobobo2bo2bo3bo3bo2bo2bo3bo3bo2bo2$4bobobo2bobo3bo3bo 2bo203bo4bobobo2bo3bo2bo3bo2bobo4bo3bo3bobo3bo$58b2o239bo$57bobo238b2o $59bo238bobo16$59bo$58bo$58b3o264bo$3bobobo4bo4bobobo2bobobo2bobo193bo 3bo4bo2bobobo2bobobo2bobo5bobo3bo3bo4bo4bo4bo4bobo3bobobo22bo$35bo221b o66b3o$3bo7bobo5bo4bo6bo195bo3bobo2bo4bo4bo6bo6bo3bo2bo3bo3bobo3bobo2b o2bo7bo$35bo221bo$3bobobo2bo3bo4bo4bobobo2bobo193bo3bo2bobo4bo4bobobo 2bobo4bo6bobobo2bo3bo2bo2bobo2bo2bobo2bobobo$57bo$3bo6bobobo4bo4bo6bo 2bo21b2o169bo3bo4bo4bo4bo6bo2bo3bo3bo2bo3bo2bobobo2bo4bo2bo4bo2bo26b3o $56bobo265bo$3bobobo2bo3bo4bo4bobobo2bo3bo191bo3bo4bo4bo4bobobo2bo3bo 3bobo3bo3bo2bo3bo2bo4bo4bobo3bobobo23bo11$305b2o$306bo9$55bo16bo237bo$ 2bobo5bobo3bo4bo2bobo27bo16bo155bobobo2bo14bobo3bo6bo3bobo4bobobo2bobo 26bo$6bo47b3o14b3o210bo24b3o$2bo6bo3bo2bobo2bo2bo3bo200bo4bo7bo4bo7bo 6bo3bo3bo2bo6bo$6bo277bo$2bobo4bo3bo2bo2bobo2bo3bo200bo4bo5bobobo2bo2b obo2bo6bo3bo3bo2bobobo2bobo2$2bo6bo3bo2bo4bo2bo3bo200bo4bo7bo4bo4bo2bo 6bo3bo3bo2bo6bo2bo26b3o$310bo$2bo7bobo3bo4bo2bobo46bo155bo4bobobo10bob o3bobobo2bo3bobo4bobobo2bo3bo26bo$50b2o20b2o$51b2o19bobo$50bo19$2bobo 5bo7bobo4bo7bobo4bobo3bo3bo2$2bo3bo3bo7bo3bo2bo6bo3bo2bo3bo2bo2bo28bo 239bo$77bo239bo$2bobo5bo2bobo2bobo4bo6bo3bo2bo6bobo28b3o237b3o$229bobo 4bobo3bobobo3bobo3bo5bo3bo3bo4bo3bobo$2bo3bo3bo7bo3bo2bo6bo3bo2bo3bo2b o2bo$228bo3bo2bo3bo4bo4bo3bo2bobobobo3bo3bobo2bo2bo3bo$2bobo5bo7bobo4b obobo3bobo4bobo3bo3bo$228bo3bo2bo8bo4bo3bo2bo2bo2bo3bo3bo2bobo2bo3bo$ 77b3o$77bo150bo3bo2bo3bo4bo4bo3bo2bo5bo3bo3bo4bo2bo3bo$78bo$229bobo4bo bo5bo5bobo3bo5bo3bo3bo4bo3bobo26b2o$307bobo$309bo7$276b2o37b2o$277bo 38bo6$112bo13bo$2bo6bobo5bo4bobobo9bobo4bo6bo3bo4bo2bo3bo2bobobo2bobo 32bo13bo$80bo30b3o11b3o$2bo5bo3bo3bobo3bo8bo4bo3bo2bo6bo3bobo2bo2bo2bo 3bo6bo$80bo$2bo5bo3bo2bo3bo2bobobo2bobobo2bobo4bo6bo3bo2bobo2bobo4bobo bo2bobo2$2bo5bo3bo2bobobo2bo8bo4bo3bo2bo6bo3bo4bo2bo2bo3bo6bo2bo2$2bob obo2bobo3bo3bo2bo13bobo4bobobo2bo3bo4bo2bo3bo2bobobo2bo3bo$107b2o21b2o 195bo$107bobo20bobo193bo$107bo22bo98bobobo9bobo3bo6bo3bobo4bobobo2bobo 7bo5bo2bobobo3bobo3bobo16b3o$278bo$233bo7bo7bo6bo3bo3bo2bo6bo9bobobobo 2bo6bo5bo$278bo$229bobobo2bobo2bo2bobo2bo6bo3bo3bo2bobobo2bobo7bo2bo2b o2bobobo3bobo3bobo2$229bo11bo4bo2bo6bo3bo3bo2bo6bo2bo6bo5bo2bo10bo5bo$ 324bo$229bobobo9bobo3bobobo2bo3bobo4bobobo2bo3bo5bo5bo2bobobo3bobo3bob o13b2o$323bobo7$69bo$68bo$46bo21b3o34bo$3bo5bo3bo3bobo4bobo18bo58bo$ 45b3o56b3o$3bobobobo3bo2bo6bo3bo2$3bo2bo2bo3bo3bobo3bo2$3bo5bo3bo6bo2b o3bo19b3o$47bo24b2o17b3o177b2o32b2o$3bo5bo3bo3bobo4bobo21bo23bobo18bo 178bo33bo$72bo19bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ WIDTH 1200 HEIGHT 1200 ZOOM 3 ]]
All 71 distinct 2-glider collisions, arranged by what they synthesize
(click above to open LifeViewer)
RLE: here Plaintext: here

See also

References

  1. Dave Greene (August 14, 2022). Re: Suggested LifeWiki edits (discussion thread) at the ConwayLife.com forums
  2. Carson Cheng (April 6, 2023). Re: Small Spaceship Syntheses (discussion thread) at the ConwayLife.com forums
  3. Mark D. Niemiec (June 20, 2015). Re: 4 glider syntheses (discussion thread) at the ConwayLife.com forums
  4. Constructions Known for All Still Lifes up to 17 Bits at Game of Life News. Posted by Dave Greene on May 23, 2014.
  5. Martin Grant (January 6, 2014). 17-bit SL Syntheses (100% Complete!) (discussion thread) at the ConwayLife.com forums
  6. Martin Grant (May 17, 2014). Re: 17-bit SL Syntheses (discussion thread) at the ConwayLife.com forums
  7. Ian07 (October 9, 2019). Re: 18-bit SL Syntheses (100% Complete!) (discussion thread) at the ConwayLife.com forums
  8. Martin Grant (February 8, 2020). Re: 19-bit still life syntheses (discussion thread) at the ConwayLife.com forums
  9. Martin Grant (March 12, 2021). Re: 20-bit still life syntheses (discussion thread) at the ConwayLife.com forums
  10. May13 (November 14, 2022). Re: 21-bit still life syntheses (discussion thread) at the ConwayLife.com forums
  11. May13 (August 19, 2024). Re: 22-bit still life syntheses (discussion thread) at the ConwayLife.com forums
  12. BlinkerSpawn (October 27, 2016). 15 in 15: Efficient 15-bit Synthesis Project (DONE!) (discussion thread) at the ConwayLife.com forums
  13. Martin Grant (November 19, 2016). Re: 15 in 15: Efficient 15-bit Synthesis Project (2 SLs remain) (discussion thread) at the ConwayLife.com forums
  14. Bob Shemyakin (December 20, 2016). 16 in 16: Efficient 16-bit Synthesis Project (discussion thread) at the ConwayLife.com forums
  15. Goldtiger997 (May 24, 2017). Re: 15 in 15: Efficient 15-bit Synthesis Project (2 SLs remain) (discussion thread) at the ConwayLife.com forums
  16. Tanner Jacobi (September 9, 2019). Re: 17 in 17: Efficient 17-bit synthesis project (discussion thread) at the ConwayLife.com forums
  17. Adam P. Goucher (September 19, 2020). Re: Binary slow salvos (discussion thread) at the ConwayLife.com forums
  18. Adam P. Goucher. "Syntheses". Catagolue. Retrieved on November 15, 2022.
  19. mu.sicman (400spartans) (September 2, 2024). Message in #cgol on the Conwaylife Lounge Discord server
  20. Goldtiger997 (March 8, 2021). Re: Small Spaceship Syntheses (discussion thread) at the ConwayLife.com forums
  21. Goldtiger997 (April 10, 2021). Re: Small Spaceship Syntheses (discussion thread) at the ConwayLife.com forums
  22. Mark Niemiec (January 14, 2022). Re: Small Spaceship Syntheses (discussion thread) at the ConwayLife.com forums
  23. https://conwaylife.com/forums/viewtopic.php?f=2&t=1557&start=625#p154625
  24. https://conwaylife.com/forums/viewtopic.php?f=2&t=1557&start=625#p154645
  25. Bob Shemyakin (June 16, 2014). 4 glider syntheses (discussion thread) at the ConwayLife.com forums
  26. Michael Simkin (October 24, 2014). Re: Making switch-engines (discussion thread) at the ConwayLife.com forums
  27. Luka Okanishi (March 12, 2017). Re: Thread For Your Accidental Discoveries (discussion thread) at the ConwayLife.com forums
  28. dani (March 27, 2022). Re: Small Quadratic Growth Patterns (discussion thread) at the ConwayLife.com forums
  29. dani (March 20, 2022). Re: Small Quadratic Growth Patterns (discussion thread) at the ConwayLife.com forums

External links

Forum threads