Difference between revisions of "Gun"
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{{Glossary}} | {{Glossary}} | ||
[[Image:Gosperglidergun.gif|framed|right|The first known gun, the [[Gosper glider gun]]]] | [[Image:Gosperglidergun.gif|framed|right|The first known gun, the [[Gosper glider gun]]]] | ||
A '''gun''' is a stationary pattern that emits [[spaceship]]s (or [[rake]]s) | A '''gun''' is a stationary pattern that repeatedly emits [[spaceship]]s (or [[rake]]s) forever. By far the most common type of guns are '''glider guns''', which emit [[glider]]s (the most well-known of which is the [[Gosper glider gun]]); however, guns that emit spaceships of other speeds, including [[c/2 orthogonal]], [[2c/5 orthogonal]], and [[c/12 diagonal]], have also been created. | ||
==History== | ==History== | ||
The first gun to be discovered, the [[Gosper glider gun]], was found by [[Bill Gosper]] in | The first gun to be discovered, the [[Gosper glider gun]], was found by [[Bill Gosper]] in {{year|1970}}, being the first known pattern in [[Conway's Game of Life]] to exhibit [[infinite growth]]. Since then, many guns have been constructed with various periods and that fire spaceships of various speeds. Due to simple [[glider synthesis|glider syntheses]] of the [[Types_of_spaceships#Standard_spaceship|standard spaceships]] many c/2 spaceship guns are known. The first gun that did not fire gliders or c/2 spaceships was a '''Cordergun''' (a gun that fires [[Cordership]]s) constructed by [[Jason Summers]] in July, {{year|1999}}<ref>{{cite web|url=http://entropymine.com/jason/life/status.html |title=Game of Life Status page |accessdate=October 15, 2010}}</ref> based on a synthesis of a variation of the [[7-engine Cordership]] by [[Stephen Silver]]. In March, {{year|2003}} [[Noam Elkies]] completed the synthesis of [[60P5H2V0]] which [[Dave Greene]] used to construct the [[P416_60P5H2V0_gun|first 2c/5 spaceship gun]] in April of the same year. | ||
In July, | In July, {{year|2010}} Dave Greene constructed a few guns for a [[gemini|geminoid]] spaceship.<ref>{{Cite web|url=http://pentadecathlon.com/lifeNews/2010/07/gemini_guns_1.html|title=Gemini guns|author=Adam P. Goucher|date=July 30, 2010|accessdate=October 15, 2010}}</ref> These are the first guns that shoot obliquely-traveling spaceships and at the time were the largest patterns constructed in Life, in terms of their bounding boxes. | ||
On February 17, {{year|2013}} [[Josh Ball]] discovered a simple [[c/7 orthogonal]] spaceship, [[loafer]]. Adam P. Goucher found a synthesis for loafer later that day, allowing the construction of c/7 orthogonal spaceship guns. | |||
During March {{year|2016}} the [[copperhead]] spaceship was discovered, with a glider synthesis and several guns following suit. | |||
==Barrels== | ==Barrels== | ||
It is not uncommon for glider guns to have multiple '''barrels'''; that is, streams of gliders that come out along multiple different paths. For example, the [[B-52 bomber]] | It is not uncommon for glider guns to have multiple '''barrels'''; that is, streams of gliders that come out along multiple different paths. For example, the [[B-52 bomber]] and [[Simkin glider gun]] are said to be double-barreled because they produce two streams of gliders. The [[period-256 glider gun]] and [[Gunstar]] and its variants all have four barrels, and [[P94S]] contains a whopping 12 barrels. Given a gun with multiple barrels, one can eliminate barrels by simply placing an [[eater 1]] in the path of the unwanted glider streams. | ||
==Pseudo-period guns== | ==Pseudo-period guns== | ||
A '''pseudo-[[period]] gun''' (as opposed to a [[#True-period guns|true-period gun]]) is a gun that emits a period n stream of spaceships (or rakes) via a mechanism that oscillates with a period different from n -- this period will necessarily be a multiple of n. Pseudo period n glider guns are known to exist for all periods greater than or equal to 14, with smaller periods being impossible. The first pseudo period 14 gun was built by [[Dietrich Leithner]] in | A '''pseudo-[[period]] gun''' (as opposed to a [[#True-period guns|true-period gun]]) is a gun that emits a period n stream of spaceships (or rakes) via a mechanism that oscillates with a period different from n -- this period will necessarily be a multiple of n. Pseudo period n glider guns are known to exist for all periods greater than or equal to 14, with smaller periods being impossible. The first pseudo period 14 gun was built by [[Dietrich Leithner]] in {{year|1995}}. | ||
==True-period guns== | ==True-period guns== | ||
A '''true-period gun''' (as opposed to a [[#Pseudo-period guns|pseudo-period gun]]) is a gun that emits a period n stream of spaceships (or rakes) via a mechanism that oscillates with period equal to n. True period n guns are known to exist for all periods greater than | A '''true-period gun''' (as opposed to a [[#Pseudo-period guns|pseudo-period gun]]) is a gun that emits a period n stream of spaceships (or rakes) via a mechanism that oscillates with period equal to n. True period n guns are known to exist for all periods greater than 53<ref>{{Cite web|url=http://www.radicaleye.com/lifepage/patterns/bhept/bhept.html|title=My Experience with B-heptominos in Oscillators|author=Dave Buckingham|accessdate=May 14, 2009|date=October 12, 1996)}}</ref>, but only a few smaller periods have been achieved, namely [[Period-20 glider gun|20]], [[True period_22 gun|22]], [[True period 24 gun|24]], [[Gosper glider gun|30]], [[Period-33 glider gun|33]], [[Period-36 glider gun|36]], [[Period-40 glider gun|40]], [[P44 pi-heptomino hassler|44]], [[Period-45 glider gun|45]], [[New gun 1|46]], [[True period 24 gun|48]], [[Period-50 glider gun|50]], [[Period-52 glider gun|52]]. Credits for gun periods below 62 are as follows: | ||
<table border="0" cellpadding="0" cellspacing="0" width="100%"><tr> | |||
{| class="wikitable" | |||
|- | |||
! Period | |||
! Discoverer | |||
! Year of discovery | |||
|- | |||
! [[Period-20 glider gun|20]] | |||
| [[Matthias Merzenich]] and [[Noam Elkies]] | |||
| {{year|2013}} | |||
|- | |||
! [[true_period_22_gun|22]] | |||
| [[David Eppstein]] and [[Jason Summers]] | |||
| {{year|2000}} | |||
|- | |||
! [[true_period_24_gun|24]] | |||
| Noam Elkies | |||
| {{year|1997}} | |||
|- | |||
! [[Gosper_glider_gun|30]] | |||
| [[Bill Gosper]] | |||
| {{year|1970}} | |||
|- | |||
! [[Period-33 glider gun|33]] | |||
| [[Arie Paap]] and Matthias Merzenich | |||
| {{year|2018}} | |||
|- | |||
! [[Period-36 glider gun|36]] | |||
| Jason Summers | |||
| {{year|2004}} | |||
|- | |||
! [[Period-40 glider gun|40]] | |||
| [[Adam P. Goucher]], Jason Summers, and Matthias Merzenich | |||
| {{year|2013}} | |||
|- | |||
! [[p44_pi-heptomino_hassler|44]] | |||
| [[David Buckingham]] | |||
| {{year|1992}} | |||
|- | |||
! [[period-45_glider_gun|45]] | |||
| Matthias Merzenich | |||
| {{year|2010}} | |||
|- | |||
! [[new_gun_1|46]] | |||
| Bill Gosper | |||
| {{year|1971}} | |||
|- | |||
! [[Period-48 glider gun|48]] | |||
| Noam Elkies | |||
| {{year|1997}} | |||
|- | |||
! [[Period-50 glider gun|50]] | |||
| [[Dean Hickerson]] and Noam Elkies | |||
| {{year|1996}} | |||
|- | |||
! [[Period-52 glider gun|52]] | |||
| [[Dave Greene]], Chris Cain, Matthias Merzenich and Adam P. Goucher | |||
| {{year|2018}} | |||
|- | |||
! [[Quetzal#Quetzal-54|54]] | |||
| [[Dietrich Leithner]] | |||
| {{year|1998}} | |||
|- | |||
! [[Quetzal#Quetzal-55|55]] | |||
| [[Stephen Silver]] | |||
| {{year|1998}} | |||
|- | |||
! [[Quetzal#Quetzal-56|56]] | |||
| Dietrich Leithner | |||
| {{year|1998}} | |||
|- | |||
! [[Quetzal#Quetzal-57|57]] | |||
| Matthias Merzenich | |||
| {{year|2016}} | |||
|- | |||
! [[Quetzal#Quetzal-58|58]] | |||
| [[thunk]] and Matthias Merzenich | |||
| {{year|2016}} | |||
|- | |||
! [[period-59_glider_gun|59]] | |||
| Adam P. Goucher and Jason Summers | |||
| {{year|2009}} | |||
|- | |||
! [[period-60_glider_gun|60]] | |||
| Bill Gosper | |||
| {{year|1970}} | |||
|- | |||
! [[Period-61 glider gun|61]] | |||
| Luka Okanishi | |||
| {{year|2016}} | |||
|} | |||
==Guns in Life-like cellular automata== | ==Guns in Life-like cellular automata== | ||
Due to the existence of some small spaceships in [[Cellular_automaton#Life-like_cellular_automata|Life-like cellular automata]] with birth at two live neighbours (B2), many low-period spaceship guns have been found using tools such as [[WinLifeSearch]]. In contrast, there are very few rules without B2 that are known to contain guns. The following is a list of rules | Due to the existence of some small spaceships in [[Cellular_automaton#Life-like_cellular_automata|Life-like cellular automata]] with birth at two live neighbours (B2), many low-period spaceship guns have been found using tools such as [[WinLifeSearch]]. In contrast, there are very few outer-totalistic rules without B2 (and B0) that are known to contain guns. The following is a list of outer-totalistic rules with neither B0 nor B2 that have known guns: | ||
{| style="width:100%" | | {| style="width:100%" | | ||
|- | |- | ||
| valign="top" width="50%" | | | valign="top" width="50%" | | ||
* Glider guns | * Glider guns<ref>{{cite web|url=http://conwaylife.com/forums/viewtopic.php?f=11&t=1071|title=Guns in Life-like cellular automata|author=[[Matthias Merzenich]] (Sokwe)|date=April 11, 2013}}</ref> | ||
** B3/S23 ([[Conway's Game of Life]]) | ** B3/S23 ([[Conway's Game of Life]]) | ||
** B3/S236 | ** B3/S236 | ||
Line 30: | Line 126: | ||
** B3/S237 | ** B3/S237 | ||
** B3/S2378 | ** B3/S2378 | ||
** B3/S238 | ** B3/S238 ([[EightLife]]) | ||
** B36/S23 ([[HighLife]]) | ** B36/S23 ([[HighLife]]) | ||
** B36/S237 | ** B36/S237 | ||
Line 36: | Line 132: | ||
** B36/S238 | ** B36/S238 | ||
** B368/S23 | ** B368/S23 | ||
** B368/S238 | ** B368/S238 ([[LowDeath]]) | ||
** B37/S23 ([[DryLife]]) | ** B37/S23 ([[DryLife]]) | ||
** B37/S236 | |||
** B37/S237 | ** B37/S237 | ||
** B37/S238 | ** B37/S238 | ||
** B378/S23 - no explicit constructions exist | |||
** B378/S237 | ** B378/S237 | ||
** B378/S2378 | ** B378/S2378 | ||
** B378/S238 | |||
** B38/S236 | ** B38/S236 | ||
** B38/S2367 | ** B38/S2367 | ||
** B38/S23678 | ** B38/S23678 | ||
** B38/S2368 | ** B38/S2368 | ||
** B38/S23 | ** B38/S23 ([[Pedestrian Life]]) | ||
** B38/S237 | ** B38/S237 | ||
** B38/S2378 | ** B38/S2378 | ||
** B38/S238 | ** B38/S238 ([[HoneyLife]]) | ||
| valign="top" | | | valign="top" | | ||
* Other guns | * Other guns | ||
** B3/S23 (Conway's Game of Life) | ** B3/S23 ([[Conway's Game of Life]]) | ||
** B3/S237 | ** B3/S237 | ||
** B3/S2378 | ** B3/S2378 | ||
** B3/S238 | ** B3/S238 ([[EightLife]]) | ||
** B35/S236 | ** B35/S236 | ||
** B358/S236 | ** B358/S236 | ||
** B36/S23 (HighLife) | ** B36/S23 ([[HighLife]]) | ||
** B36/S237 | ** B36/S237 | ||
** B36/S2378 | ** B36/S2378 | ||
** B36/S238 | ** B36/S238 | ||
** B368/S23 | ** B368/S23 | ||
** B368/S238 | ** B368/S238 ([[LowDeath]]) | ||
** B36/S245 ([http://www.ics.uci.edu/~eppstein/ca/replicators/b36s245.html Logarithmic replicator rule]) | ** B36/S245 ([http://www.ics.uci.edu/~eppstein/ca/replicators/b36s245.html Logarithmic replicator rule]) | ||
** B368/S245 ([[Move]]) | ** B368/S245 ([[Move]]) | ||
** B368/S12578 | ** B368/S12578 | ||
** B3678/S34678 ([[Day & Night]]) | ** B3678/S34678 ([[Day & Night]]) | ||
** B37/S23 (DryLife) | ** B37/S23 ([[DryLife]]) | ||
** B37/S238 | ** B37/S238 | ||
** B38/S23 | ** B378/S23 | ||
** B378/S238 | |||
** B38/S23 ([[Pedestrian Life]]) | |||
** B38/S237 | ** B38/S237 | ||
** B38/S2378 | ** B38/S2378 | ||
** B38/S238 | ** B38/S238 ([[HoneyLife]]) | ||
|} | |} | ||
==See also== | ==See also== | ||
*[[Dieter and Peter's glider gun collection]] | |||
*[[LifeWiki:Game_of_Life_Status_page#Glider_gun_true-periods|Glider gun true-periods status table]] | |||
*[[LifeWiki:Game_of_Life_Status_page#Gun_pseudo-periods|Gun pseudo-periods status table]] | |||
*[[:Category:Guns|List of guns]] | *[[:Category:Guns|List of guns]] | ||
*[[Quetzal]] | |||
==References== | ==References== | ||
Line 83: | Line 189: | ||
==External links== | ==External links== | ||
{{LinkWikipedia|Gun_(cellular_automaton)}} | |||
{{LinkWeisstein|Gun.html}} | {{LinkWeisstein|Gun.html}} | ||
{{LinkLexicon|lex_g.htm#gun}} | {{LinkLexicon|lex_g.htm#gun}} |
Revision as of 19:46, 28 December 2019
A gun is a stationary pattern that repeatedly emits spaceships (or rakes) forever. By far the most common type of guns are glider guns, which emit gliders (the most well-known of which is the Gosper glider gun); however, guns that emit spaceships of other speeds, including c/2 orthogonal, 2c/5 orthogonal, and c/12 diagonal, have also been created.
History
The first gun to be discovered, the Gosper glider gun, was found by Bill Gosper in 1970, being the first known pattern in Conway's Game of Life to exhibit infinite growth. Since then, many guns have been constructed with various periods and that fire spaceships of various speeds. Due to simple glider syntheses of the standard spaceships many c/2 spaceship guns are known. The first gun that did not fire gliders or c/2 spaceships was a Cordergun (a gun that fires Corderships) constructed by Jason Summers in July, 1999[1] based on a synthesis of a variation of the 7-engine Cordership by Stephen Silver. In March, 2003 Noam Elkies completed the synthesis of 60P5H2V0 which Dave Greene used to construct the first 2c/5 spaceship gun in April of the same year.
In July, 2010 Dave Greene constructed a few guns for a geminoid spaceship.[2] These are the first guns that shoot obliquely-traveling spaceships and at the time were the largest patterns constructed in Life, in terms of their bounding boxes.
On February 17, 2013 Josh Ball discovered a simple c/7 orthogonal spaceship, loafer. Adam P. Goucher found a synthesis for loafer later that day, allowing the construction of c/7 orthogonal spaceship guns.
During March 2016 the copperhead spaceship was discovered, with a glider synthesis and several guns following suit.
Barrels
It is not uncommon for glider guns to have multiple barrels; that is, streams of gliders that come out along multiple different paths. For example, the B-52 bomber and Simkin glider gun are said to be double-barreled because they produce two streams of gliders. The period-256 glider gun and Gunstar and its variants all have four barrels, and P94S contains a whopping 12 barrels. Given a gun with multiple barrels, one can eliminate barrels by simply placing an eater 1 in the path of the unwanted glider streams.
Pseudo-period guns
A pseudo-period gun (as opposed to a true-period gun) is a gun that emits a period n stream of spaceships (or rakes) via a mechanism that oscillates with a period different from n -- this period will necessarily be a multiple of n. Pseudo period n glider guns are known to exist for all periods greater than or equal to 14, with smaller periods being impossible. The first pseudo period 14 gun was built by Dietrich Leithner in 1995.
True-period guns
A true-period gun (as opposed to a pseudo-period gun) is a gun that emits a period n stream of spaceships (or rakes) via a mechanism that oscillates with period equal to n. True period n guns are known to exist for all periods greater than 53[3], but only a few smaller periods have been achieved, namely 20, 22, 24, 30, 33, 36, 40, 44, 45, 46, 48, 50, 52. Credits for gun periods below 62 are as follows:
Period | Discoverer | Year of discovery |
---|---|---|
20 | Matthias Merzenich and Noam Elkies | 2013 |
22 | David Eppstein and Jason Summers | 2000 |
24 | Noam Elkies | 1997 |
30 | Bill Gosper | 1970 |
33 | Arie Paap and Matthias Merzenich | 2018 |
36 | Jason Summers | 2004 |
40 | Adam P. Goucher, Jason Summers, and Matthias Merzenich | 2013 |
44 | David Buckingham | 1992 |
45 | Matthias Merzenich | 2010 |
46 | Bill Gosper | 1971 |
48 | Noam Elkies | 1997 |
50 | Dean Hickerson and Noam Elkies | 1996 |
52 | Dave Greene, Chris Cain, Matthias Merzenich and Adam P. Goucher | 2018 |
54 | Dietrich Leithner | 1998 |
55 | Stephen Silver | 1998 |
56 | Dietrich Leithner | 1998 |
57 | Matthias Merzenich | 2016 |
58 | thunk and Matthias Merzenich | 2016 |
59 | Adam P. Goucher and Jason Summers | 2009 |
60 | Bill Gosper | 1970 |
61 | Luka Okanishi | 2016 |
Guns in Life-like cellular automata
Due to the existence of some small spaceships in Life-like cellular automata with birth at two live neighbours (B2), many low-period spaceship guns have been found using tools such as WinLifeSearch. In contrast, there are very few outer-totalistic rules without B2 (and B0) that are known to contain guns. The following is a list of outer-totalistic rules with neither B0 nor B2 that have known guns:
|
|
See also
- Dieter and Peter's glider gun collection
- Glider gun true-periods status table
- Gun pseudo-periods status table
- List of guns
- Quetzal
References
- ↑ "Game of Life Status page". Retrieved on October 15, 2010.
- ↑ Adam P. Goucher (July 30, 2010). "Gemini guns". Retrieved on October 15, 2010.
- ↑ Dave Buckingham (October 12, 1996)). "My Experience with B-heptominos in Oscillators". Retrieved on May 14, 2009.
- ↑ Matthias Merzenich (Sokwe) (April 11, 2013). "Guns in Life-like cellular automata".
External links
- Gun at Wikipedia
- Gun at the Life Lexicon