Difference between revisions of "Gun"

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==History==
 
==History==
The first gun to be discovered, the [[Gosper glider gun]], was found by [[Bill Gosper]] in [[:Category:patterns found in 1970|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, [[:Category:patterns found in 1999|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, [[:Category:patterns found in 2003|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.
+
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, [[:Category:patterns found in 2010|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.
+
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, [[:Category:patterns found in 2013|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.
+
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.<ref name="post7466" />
  
During March [[:Category:patterns found in 2016|2016]] the [[Copperhead]] spaceship was discovered, with a glider synthesis and several guns following suit.
+
During March {{year|2016}} the [[copperhead]] spaceship was discovered, with a glider synthesis and several guns following suit.<ref name="post28101" />
 +
 
 +
In {{year|2019}} and {{year|2020}} guns were produced for the spaceships [[46P4H1V0]],<ref name="post84423" /> [[spider]],<ref name="post88186" /> and [[58P5H1V1]],<ref name="post97489" /> of speeds [[c/4 orthogonal]], [[c/5 orthogonal]], and [[c/5 diagonal]] respectively.
  
 
==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]] and [[Simkin glider gun]] is said to be double-barreled because it produces 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.
+
The '''barrel''' of a gun (or rake) is a path along which spaceships travel. The term is most commonly used in the context of the number of barrels a gun or rake possesses, which is the number of distinct spaceship streams emitted by said gun or rake. For example, the [[AK-94]], [[B-52 bomber]] and [[Simkin glider gun]] are said to be '''double-barrelled''' 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 [[:Category:Patterns found in 1995|1995]].
+
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 {{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 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:
+
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>
 
<table border="0" cellpadding="0" cellspacing="0" width="100%"><tr>
Line 30: Line 32:
 
! [[Period-20 glider gun|20]]
 
! [[Period-20 glider gun|20]]
 
| [[Matthias Merzenich]] and [[Noam Elkies]]
 
| [[Matthias Merzenich]] and [[Noam Elkies]]
| [[:Category:Patterns found in 2013|2013]]
+
| {{year|2013}}
 
|-
 
|-
 
! [[true_period_22_gun|22]]
 
! [[true_period_22_gun|22]]
 
| [[David Eppstein]] and [[Jason Summers]]
 
| [[David Eppstein]] and [[Jason Summers]]
| [[:Category:Patterns found in 2000|2000]]
+
| {{year|2000}}
 
|-
 
|-
 
! [[true_period_24_gun|24]]
 
! [[true_period_24_gun|24]]
 
| Noam Elkies
 
| Noam Elkies
| [[:Category:Patterns found in 1997|1997]]
+
| {{year|1997}}
 
|-
 
|-
 
! [[Gosper_glider_gun|30]]
 
! [[Gosper_glider_gun|30]]
 
| [[Bill Gosper]]
 
| [[Bill Gosper]]
| [[:Category:Patterns found in 1970|1970]]
+
| {{year|1970}}
 
|-
 
|-
 
! [[Period-33 glider gun|33]]
 
! [[Period-33 glider gun|33]]
 
| [[Arie Paap]] and Matthias Merzenich
 
| [[Arie Paap]] and Matthias Merzenich
| [[:Category:Patterns found in 2018|2018]]
+
| {{year|2018}}
 
|-
 
|-
 
! [[Period-36 glider gun|36]]
 
! [[Period-36 glider gun|36]]
 
| Jason Summers
 
| Jason Summers
| [[:Category:Patterns found in 2004|2004]]
+
| {{year|2004}}
 
|-
 
|-
 
! [[Period-40 glider gun|40]]
 
! [[Period-40 glider gun|40]]
 
| [[Adam P. Goucher]], Jason Summers, and Matthias Merzenich
 
| [[Adam P. Goucher]], Jason Summers, and Matthias Merzenich
| [[:Category:Patterns found in 2013|2013]]
+
| {{year|2013}}
 
|-
 
|-
 
! [[p44_pi-heptomino_hassler|44]]
 
! [[p44_pi-heptomino_hassler|44]]
 
| [[David Buckingham]]
 
| [[David Buckingham]]
| [[:Category:Patterns found in 1992|1992]]
+
| {{year|1992}}
 
|-
 
|-
 
! [[period-45_glider_gun|45]]
 
! [[period-45_glider_gun|45]]
 
| Matthias Merzenich
 
| Matthias Merzenich
| [[:Category:Patterns found in 2010|2010]]
+
| {{year|2010}}
 
|-
 
|-
 
! [[new_gun_1|46]]
 
! [[new_gun_1|46]]
 
| Bill Gosper
 
| Bill Gosper
| [[:Category:Patterns found in 1971|1971]]
+
| {{year|1971}}
 
|-
 
|-
 
! [[Period-48 glider gun|48]]
 
! [[Period-48 glider gun|48]]
 
| Noam Elkies
 
| Noam Elkies
| [[:Category:Patterns found in 1997|1997]]
+
| {{year|1997}}
 
|-
 
|-
 
! [[Period-50 glider gun|50]]
 
! [[Period-50 glider gun|50]]
 
| [[Dean Hickerson]] and Noam Elkies
 
| [[Dean Hickerson]] and Noam Elkies
| [[:Category:Patterns found in 1996|1996]]
+
| {{year|1996}}
 
|-
 
|-
 
! [[Period-52 glider gun|52]]
 
! [[Period-52 glider gun|52]]
 
| [[Dave Greene]], Chris Cain, Matthias Merzenich and Adam P. Goucher
 
| [[Dave Greene]], Chris Cain, Matthias Merzenich and Adam P. Goucher
| [[:Category:Patterns found in 2018|2018]]
+
| {{year|2018}}
 
|-
 
|-
 
! [[Quetzal#Quetzal-54|54]]
 
! [[Quetzal#Quetzal-54|54]]
 
| [[Dietrich Leithner]]
 
| [[Dietrich Leithner]]
| [[:Category:Patterns found in 1998|1998]]
+
| {{year|1998}}
 
|-
 
|-
 
! [[Quetzal#Quetzal-55|55]]
 
! [[Quetzal#Quetzal-55|55]]
 
| [[Stephen Silver]]
 
| [[Stephen Silver]]
| [[:Category:Patterns found in 1998|1998]]
+
| {{year|1998}}
 
|-
 
|-
 
! [[Quetzal#Quetzal-56|56]]
 
! [[Quetzal#Quetzal-56|56]]
 
| Dietrich Leithner
 
| Dietrich Leithner
| [[:Category:Patterns found in 1998|1998]]
+
| {{year|1998}}
 
|-
 
|-
 
! [[Quetzal#Quetzal-57|57]]
 
! [[Quetzal#Quetzal-57|57]]
 
| Matthias Merzenich
 
| Matthias Merzenich
| [[:Category:Patterns found in 2016|2016]]
+
| {{year|2016}}
 
|-
 
|-
 
! [[Quetzal#Quetzal-58|58]]
 
! [[Quetzal#Quetzal-58|58]]
 
| [[thunk]] and Matthias Merzenich
 
| [[thunk]] and Matthias Merzenich
| [[:Category:Patterns found in 2016|2016]]
+
| {{year|2016}}
 
|-
 
|-
 
! [[period-59_glider_gun|59]]
 
! [[period-59_glider_gun|59]]
 
| Adam P. Goucher and Jason Summers
 
| Adam P. Goucher and Jason Summers
| [[:Category:Patterns found in 2009|2009]]
+
| {{year|2009}}
 
|-
 
|-
 
! [[period-60_glider_gun|60]]
 
! [[period-60_glider_gun|60]]
 
| Bill Gosper
 
| Bill Gosper
| [[:Category:Patterns found in 1970|1970]]
+
| {{year|1970}}
 
|-
 
|-
 
! [[Period-61 glider gun|61]]
 
! [[Period-61 glider gun|61]]
 
| Luka Okanishi
 
| Luka Okanishi
| [[:Category:Patterns found in 2016|2016]]
+
| {{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 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:
+
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:
 
{| style="width:100%" |
 
{| style="width:100%" |
 
|-
 
|-
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==References==
 
==References==
<references />
+
<references>
 +
<ref name="post7466">{{LinkForumThread
 +
|format    = ref
 +
|title      = Re: c/7 orthogonal spaceships
 +
|p          = 7466
 +
|author    = Shannon Omick
 +
|date      = February 18, 2013
 +
}}</ref>
 +
<ref name="post28101">{{LinkForumThread
 +
|format    = ref
 +
|title      = Re: is this c/10 spaceship known?
 +
|p          = 28101
 +
|author    = Alexey Nigin
 +
|date      = March 6, 2016
 +
}}</ref>
 +
<ref name="post84423">{{LinkForumThread
 +
|format = ref
 +
|title  = Re: Stable signal converters
 +
|p      = 84423
 +
|author = Goldtiger997
 +
|date  = October 22, 2019
 +
}}</ref>
 +
<ref name="post88186">{{LinkForumThread
 +
|format = ref
 +
|title  = Re: Small Spaceship Syntheses
 +
|p      = 88186
 +
|author = Entity Valkyrie
 +
|date  = January 26, 2020
 +
}}</ref>
 +
<ref name="post97489">{{LinkForumThread
 +
|format = ref
 +
|title  = Re: Construction practice
 +
|p      = 97489
 +
|author = Entity Valkyrie
 +
|date  = May 22, 2020
 +
}}</ref>
 +
</references>
  
 
==External links==
 
==External links==
 
{{LinkWikipedia|Gun_(cellular_automaton)}}
 
{{LinkWikipedia|Gun_(cellular_automaton)}}
{{LinkWeisstein|Gun.html}}
 
 
{{LinkLexicon|lex_g.htm#gun}}
 
{{LinkLexicon|lex_g.htm#gun}}
 +
{{LinkLexicon|filename=lex_d.htm#doublebarrelled|patternname=Double-barrelled}}
 +
{{LinkForumThread|f=2|t=1657|title=Execution of Old Guns by Variable-Speed Firing Squad}}

Latest revision as of 05:25, 4 June 2020

The first known gun, the Gosper glider gun

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.[3]

During March 2016 the copperhead spaceship was discovered, with a glider synthesis and several guns following suit.[4]

In 2019 and 2020 guns were produced for the spaceships 46P4H1V0,[5] spider,[6] and 58P5H1V1,[7] of speeds c/4 orthogonal, c/5 orthogonal, and c/5 diagonal respectively.

Barrels

The barrel of a gun (or rake) is a path along which spaceships travel. The term is most commonly used in the context of the number of barrels a gun or rake possesses, which is the number of distinct spaceship streams emitted by said gun or rake. For example, the AK-94, B-52 bomber and Simkin glider gun are said to be double-barrelled 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-periodgun) 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[8], 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:

  • Glider guns[9]
    • B3/S23 (Conway's Game of Life)
    • B3/S236
    • B3/S2367
    • B3/S23678
    • B3/S2368
    • B3/S237
    • B3/S2378
    • B3/S238 (EightLife)
    • B36/S23 (HighLife)
    • B36/S237
    • B36/S2378
    • B36/S238
    • B368/S23
    • B368/S238 (LowDeath)
    • B37/S23 (DryLife)
    • B37/S236
    • B37/S237
    • B37/S238
    • B378/S23 - no explicit constructions exist
    • B378/S237
    • B378/S2378
    • B378/S238
    • B38/S236
    • B38/S2367
    • B38/S23678
    • B38/S2368
    • B38/S23 (Pedestrian Life)
    • B38/S237
    • B38/S2378
    • B38/S238 (HoneyLife)

See also

References

  1. "Game of Life Status page". Retrieved on October 15, 2010.
  2. Adam P. Goucher (July 30, 2010). "Gemini guns". Retrieved on October 15, 2010.
  3. Shannon Omick (February 18, 2013). Re: c/7 orthogonal spaceships (discussion thread) at the ConwayLife.com forums
  4. Alexey Nigin (March 6, 2016). Re: is this c/10 spaceship known? (discussion thread) at the ConwayLife.com forums
  5. Goldtiger997 (October 22, 2019). Re: Stable signal converters (discussion thread) at the ConwayLife.com forums
  6. Entity Valkyrie (January 26, 2020). Re: Small Spaceship Syntheses (discussion thread) at the ConwayLife.com forums
  7. Entity Valkyrie (May 22, 2020). Re: Construction practice (discussion thread) at the ConwayLife.com forums
  8. Dave Buckingham (October 12, 1996). "My Experience with B-heptominos in Oscillators". Retrieved on May 14, 2009.
  9. Matthias Merzenich (Sokwe) (April 11, 2013). "Guns in Life-like cellular automata".

External links

  • Gun at Wikipedia