# 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.
July 14 & 21, 2023 3.7 73 "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.

## Errata and Typos

Section Pages Notes
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"
11.7.3, 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).