Conway's Game of Life: Mathematics and Construction/Errata

This page is intended to catalogue any anachronisms or typos found in the book Conway's Game of Life: Mathematics and Construction.

Anachronisms

The book is up-to-date as of January 15, 2022. The discoveries listed here are all from after that date.

Date	Section	Pages	Notes
January 29, 2022	8.5	234	Table 8.1 does not include the period-27 glider gun found by goldenratio and hotdogPi.
February 14, 2022	8.5	236	JP21 found a new (smaller) p28 gun, making the sentence "The only known true-period 28 glider gun is also based on hassling a T-tetromino..." no longer true.
April 12, 2022	8.5.1	233-4	iNoMed and David Raucci have assembled a single-engine p36 gun. Nothing in the book is technically incorrect, but "36" is now a slight anachronism in the section title "Spark Collisions: True-Period 22, 30, 33, 36, 45, and 46 Guns"
June 25, 2022	8.5.2	234-6	iNoMed and cvojan have built guns based on a new p37 R-hassling oscillator, which is not in the table. "37" should now be included in the 8.5.2 section title.
July 6, 2022	3.7	73	"34" can be removed from the list of unknown periods.
November 2, 2022	Exercise 8.17	265	Period 51 now has a very simple honeyfarm hassler gun as well as the larger one based on the hotcrystal0 reaction. Nothing in the book seems to be inaccurate, but possibly a reference to the smaller p51 could be added in the footnote.
November 8, 2022	8.5.2	234-6	"25" can be added to the table due to this p25 gun. It's a "modified B-heptomino hassler", so it could be added to the hasslers section, but maybe that object isn't common enough to count as "common".
January 12, 2023	4.6.1	106-107	A fifth elementary diagonal spaceship speed has been discovered, the c/8 Walrus.
April 5, 2023 (p61 glider gun) and/or July 24, 2022 (speed tunnel)	8.5.2	234-6	"61" can be added to the hasslers section due to this p61 gun. But also the p61 and p62 lines could simply be cut from the table, and explanatory text could say that all periods 61 and above can be achieved with speed tunnels and a carefully chosen subset of Herschel tracks.
June 6, 2023	4.6.1, 10.5	108, 337-340	A spaceship was constructed via the (34,7)c/156 Herschel climber, attaining a speed of (34,7)c/156 and a slope of 34/7
July 14 & 21, 2023	3.7, 4.5.1	73-74, 101-103	"19" and "41" can be removed from the list of unknown periods (which can be made empty); 2023 can be added as a year in which new periods were discovered, and Life was proven omniperiodic.
November 15, 2022 (21-bitters) August 19, 2024 (22-bitters) December 27, 2025 (23-bitters)	5.3, 5.8	129, 147	Syntheses have since been found for all 21-bit strict still lifes, all 22-bit strict still lifes, and all 23-bit strict still lifes
September 11, 2022 & January 31, 2023	3.5	68	Period-43 glider gun and 94P53 mean that periods 43 and 53 are no longer only achievable with snark loops
October 28-30, 2024	8.5.2	234-6	There is now a true period-47 glider gun by iNoMed, Entity Valkyrie, and Luka Okanishi.
December 5, 2024	8.5.2	234-6	There is now a true period-35 glider gun by iNoMed, hotcrystal0, and Matthias Merzenich.
December 14, 2024	9.4.2, Chapter 9 Exercises	288-291, 309-310	Optimized arithmetic units ADD, SUB, and MUL are now available, exactly as requested in Exercise 9.13. An APGsembly listing for a computer that prints prime numbers (Exercise 9.25) is included in the package; I think the original source is Nathaniel's posted solutions to Exercises 9.24 and 9.25.
March 16, 2025	8.5.2	234-6	There is now a true period-14 glider gun by Matthias Merzenich and James Pascua.
2024-2025	10.1.4, 10.5	321, 337	silverfish is no longer the smallest 31c/240 orthogonal spaceship, having been surpassed by leaf bug, Mannaz, water strider, and leaf bug 2
February 11, 2022	3.3.1	61	caterer is no longer used for SKOP 21 (32P21)
September 27, 2026	3.7	73	"38" can be removed from the list of unknown periods.

Errata and Typos

Section	Pages	Notes
1.8	31	Exercise 1.17 claims that a pattern stabilizes in 6526574 generations, when in reality it stabilizes in 8120878 generations.
4.5.2	103	When this happens, the wire is instead called a wick, and the objects that “burns” through the wick is called a fuse. Subject-verb disagreement.
6	154	"... typically smaller and simpler that stationary circuitry ..." should be "... typically smaller and simpler than stable circuitry ..."
6.3.3	168	In footnote 17, "stationary" should be "stable" instead.
6.6	181	There appears to be an erroneous space between problem 6.31 and its asterisk.
7.9	211	Footnote 40 appears on page 212, though the reference is on page 211.
7.9	218	There appears to be an erroneous space between problem 7.38 and its asterisk.
7.9	218	In problem 7.38, "true period" should be "true-period" as it is throughout the book.
9.8, Figure 9.17	307	(FIXED 04/23/2022 on website and PDF) Omission - the pattern file reachable by clicking Figure 9.17 has comments that imply that the pattern is Adam P. Goucher's original Osqrtlogt. An additional line should say "Partially rebuilt and reduced by Dave Greene and Nathaniel Johnston in 2019-20, using newer components like Snark and syringe."
10.2.1	322	Typo - "behind a backward rate" should be "behind a backward rake"
11.3	361	Missing number - the recipe to create a glider on lane 12 is missing a timing delay of 109 ticks at the start.
11.7.3, Figure 11.24	375	Typo - "... allowing the crab two carry two construction ..." first instance of "two" should be "to".
11.7.3, Figure 11.24	375	Typo - "... so as trigger the ignitions." should be "... so as to trigger the ignitions."
11.27	380	Typo - "bounces around the diamond-shaped track highlighted track in orange": second instance of "track" should be removed.
12.3	395	Figure 12.16 caption, "degrees). Uses the same state" → "degrees). It uses the same state"
Pattern Library		The pattern file for Chapter 4 exercise 4.28 in the library is named "beehive wire" but should be "beehive wick" (the rle file contains the correct name).

Technically Correct, but Misleading

Section	Pages	Notes
4.6.2	110	The text says that the adjustable bi-block rake of Figure 4.52 can have its period increased by 32 by adding additional bi-blocks. It should be noted that its period can also be increased by 8 by moving the front pair of rakes forward by 2 generations.
5.8	147	The text says that a 17-glider RCT mechanism was found in September 2020. That's true enough, but now it should probably say instead that a 16-glider mechanism was found in April 2022.
6.4	171	The p34 oscillator discovered in July 2022 has an optional attachment that allows a bumper mechanism to work at the minimum possible period.