Difference between revisions of "Glider"

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{{Spaceship|name=Glider|pname=glider|dir=Diagonal|p=4|s=c/4|c=5|bx=3|by=3|h=4|discoverer=Richard K. Guy|discoveryear=1970|life105=true|life106=true|plaintext=true|rle=true|animated=true}}
{{Spaceship
|name         = Glider
|pname       = glider
|c            = 5
|bx          = 3
|by          = 3
|dir         = Diagonal
|p           = 4
|m            = 2
|s           = c/4
|h           = 4
|discoverer   = Richard K. Guy
|discoveryear = 1970
|rulemin      = B3/S23
|rulemax      = B3678/S0235678
|rulespecial  = [[Conway's Game of Life|Conway Life]], [[HighLife]]
|synthesis    = 2
|synthesisRLE = true
|life105     = true
|life106     = true
|plaintext   = true
|rle         = true
|animated     = true
|viewerconfig = #C [[ TRACKLOOP 4 1/4 1/4 THUMBSIZE 3 GPS 4 ]]
}}
{{disambiglink|name=glider|text=For other meanings of the term}}
{{disambiglink|name=glider|text=For other meanings of the term}}
A '''glider''' (or '''featherweight spaceship''') is the smallest, most common, and first-discovered [[spaceship]]. Its name is due in part to the fact that it is [[glide symmetric]]. It travels diagonally across the [[Life]] grid at a speed of [[:Category:Spaceships with speed c/4|c/4]] and is often produced by randomly-generated starting [[pattern|patterns]].<ref>{{cite web|url=http://wwwhomes.uni-bielefeld.de/achim/moving.html |title=Spontaneous appeared Spaceships out of Random Dust |publisher=Achim Flammenkamp |date=December 9, 1995|accessdate=February 27, 2009}}</ref> Gliders are important because they are easily produced (for an example see the [[Gosper glider gun]]), can be collided with each other to form more complicated objects (see [[glider synthesis]]), and can be used to transmit information over long distances.
The '''glider''' (or '''featherweight spaceship''') is the smallest, most common, and first-discovered [[spaceship]]. It travels diagonally across the [[Life]] grid at a speed of [[c/4 diagonal|c/4]]. Gliders are important because they are easily produced (for an example see the [[Gosper glider gun]]), can be collided with each other to form more complicated objects (see [[glider synthesis]]), and can be used to transmit information over long distances.


The glider was found by [[:Category:Patterns found by Richard K. Guy|Richard K. Guy]] in [[:Category:Patterns found in 1970|1970]] while Conway's group was attempting to track the evolution of the [[R-pentomino]]. It is often stated that [[:Category:Patterns found by John Conway|John Conway]] discovered the glider, but he himself has said that it was Guy.
The glider was found by [[Richard K. Guy]] in [[:Category:Patterns found in 1970|1970]] while Conway's group was attempting to track the evolution of the [[R-pentomino]]. It is often stated that [[John Conway]] discovered the glider, but he himself has said that it was Guy.
 
Its name is due in part to the fact that it is [[glide symmetric]]; however, John Conway has stated he regrets calling it a glider, saying it looks more like an ant walking across the plane.<ref>{{cite web|url=https://www.youtube.com/watch?v=E8kUJL04ELA&t=3m55s|title=Does John Conway hate using Game of Life?|publisher=Numberphile|date=3 Mar 2014|accessdate=13 Jun 2016}}</ref>
 
==Commonness==
The glider is often produced by randomly-generated starting [[pattern]]s.<ref>{{cite web|url=http://wwwhomes.uni-bielefeld.de/achim/moving.html |title=Spontaneous appeared Spaceships out of Random Dust |publisher=Achim Flammenkamp |date=December 9, 1995|accessdate=February 27, 2009}}</ref>; it is the fourth most common object on [[Adam P. Goucher]]'s [[Catagolue]].<ref>{{citeCatagolueStats|June 24, 2016}}</ref>


==Glider synthesis==
==Glider synthesis==
{{main|Glider synthesis}}
{{main|Glider synthesis}}
'''Glider synthesis''' is the construction of an object by means of glider collisions. 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.
'''Glider synthesis''' is the construction of an object by means of glider collisions. 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.<ref>{{CiteLexicon|file=lex_g.htm#glidersynthesis|name=Glider synthesis|accessdate=May 21, 2009}}</ref>


Glider syntheses for all [[still life]]s and known [[oscillator]]s with at most 14 [[cell]]s have been explicitly constructed.
Glider syntheses for all [[still life]]s with at most 18 [[cell]]s<ref>{{cite web|url=http://pentadecathlon.com/lifeNews/2014/05/constructions_known_for_all_st.html |title=Constructions Known for All Still Lifes up to 17 Bits |work=Game of Life News |publisher=Dave Greene |accessdate=September 17, 2014}}</ref><ref>{{cite web|url=http://www.conwaylife.com/forums/viewtopic.php?f=2&t=1467#p13607 |title=18-bit SL Syntheses (100% Complete!)}}</ref> and known [[oscillator]]s with at most 14 cells have been explicitly constructed.


==Colour of a glider==
==Colour of a glider==
The '''colour of a glider''' is a property of the glider which remains constant while the glider is moving along a straight path, but which can be changed when the glider bounces off a [[reflector]]. It is an important consideration when building something using reflectors.
The '''colour''' (or '''parity''') of a glider is a property of the glider which remains constant while the glider is moving along a straight path, but which can be changed when the glider bounces off a [[reflector]]. It is an important consideration when building something using reflectors.


To define the colour of a glider, first choose some cell to be the origin. This cell is then considered to be white, and all other cells to be black or white in a checkerboard pattern (i.e. the cell with coordinates (m,n) is white if m+n is even, and black otherwise). Then the colour of a glider is the colour of its leading cell when it is in a [[phase]] which can be rotated or reflected to look like the above image.
To define the colour of a glider, first choose some cell to be the origin. This cell is then considered to be white, and all other cells to be black or white in a checkerboard pattern (i.e. the cell with coordinates (m,n) is white if m+n is even, and black otherwise). Then the colour of a glider is the colour of its leading cell when it is in a [[phase]] which can be rotated to look like [[:File:Glider.png|this image]].


A reflector which does not change the colour of gliders obviously can not be used to move a glider onto a path of different colour than it started on. However, a 90-degree reflector which does change the colour of gliders is similarly limited, as the colour of the resulting glider will depend only on the direction of the glider, no matter how many reflectors are used. For maximum flexibility, therefore, both types of reflector are required.<ref>{{cite web|url=http://www.argentum.freeserve.co.uk/lex_c.htm#colourofaglider |title=Colour of a glider |work=The Life Lexicon |publisher=Stephen Silver|accessdate=April 22, 2009}}</ref>
A reflector which does not change the colour of gliders obviously can not be used to move a glider onto a path of different colour than it started on. However, a 90-degree reflector which does change the colour of gliders is similarly limited, as the colour of the resulting glider will depend only on the direction of the glider, no matter how many reflectors are used. For maximum flexibility, therefore, both types of reflector are required.<ref>{{CiteLexicon|file=lex_c.htm#colourofaglider|name=Colour of a glider|accessdate=April 22, 2009}}</ref>


==See also==
==See also==
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==External links==
==External links==
*[http://www.argentum.freeserve.co.uk/lex_g.htm#glider Glider] at the Life Lexicon
{{LinkWeisstein|Glider.html}}
*[http://www.argentum.freeserve.co.uk/lex_g.htm#glidersynthesis Glider synthesis] at the Life Lexicon
{{LinkLexicon|lex_g.htm#glider}}
{{LinkEppstein|115|patternname=The Glider (glider 115)}}
{{LinkCatagolue|xq4_153}}
{{LinkNiemiec|ss.htm#ss-5|patternname=The 1 five-bit spaceship}}
{{LinkPentadecathlonObject|5P4H1V1.1}}
{{LinkWikipedia|Glider_(CA)}}
 
[[Category:Glide symmetric spaceships]]
[[Category:Glide symmetric spaceships]]

Revision as of 12:12, 23 July 2016

Glider
bob$2bo$3o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ TRACKLOOP 4 1/4 1/4 THUMBSIZE 3 GPS 4 ]]
View animated image
View static image
Pattern type Spaceship
Number of cells 5
Bounding box 3 × 3
Direction Diagonal
Period 4
Mod 2
Speed c/4 | Unknown
Heat 4
Discovered by Richard K. Guy
Year of discovery 1970
For other meanings of the term 'glider', see Glider (disambiguation).

The glider (or featherweight spaceship) is the smallest, most common, and first-discovered spaceship. It travels diagonally across the Life grid at a speed of c/4. Gliders are important because they are easily produced (for an example see the Gosper glider gun), can be collided with each other to form more complicated objects (see glider synthesis), and can be used to transmit information over long distances.

The glider was found by Richard K. Guy in 1970 while Conway's group was attempting to track the evolution of the R-pentomino. It is often stated that John Conway discovered the glider, but he himself has said that it was Guy.

Its name is due in part to the fact that it is glide symmetric; however, John Conway has stated he regrets calling it a glider, saying it looks more like an ant walking across the plane.[1]

Commonness

The glider is often produced by randomly-generated starting patterns.[2]; it is the fourth most common object on Adam P. Goucher's Catagolue.[3]

Glider synthesis

Main article: Glider synthesis

Glider synthesis is the construction of an object by means of glider collisions. 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.[4]

Glider syntheses for all still lifes with at most 18 cells[5][6] and known oscillators with at most 14 cells have been explicitly constructed.

Colour of a glider

The colour (or parity) of a glider is a property of the glider which remains constant while the glider is moving along a straight path, but which can be changed when the glider bounces off a reflector. It is an important consideration when building something using reflectors.

To define the colour of a glider, first choose some cell to be the origin. This cell is then considered to be white, and all other cells to be black or white in a checkerboard pattern (i.e. the cell with coordinates (m,n) is white if m+n is even, and black otherwise). Then the colour of a glider is the colour of its leading cell when it is in a phase which can be rotated to look like this image.

A reflector which does not change the colour of gliders obviously can not be used to move a glider onto a path of different colour than it started on. However, a 90-degree reflector which does change the colour of gliders is similarly limited, as the colour of the resulting glider will depend only on the direction of the glider, no matter how many reflectors are used. For maximum flexibility, therefore, both types of reflector are required.[7]

See also

References

  1. ↑ "Does John Conway hate using Game of Life?". Numberphile (3 Mar 2014). Retrieved on 13 Jun 2016.
  2. ↑ "Spontaneous appeared Spaceships out of Random Dust". Achim Flammenkamp (December 9, 1995). Retrieved on February 27, 2009.
  3. ↑ Adam P. Goucher. "Statistics". Catagolue. Retrieved on June 24, 2016.
  4. ↑ "Glider synthesis". The Life Lexicon. Stephen Silver. Retrieved on May 21, 2009.
  5. ↑ "Constructions Known for All Still Lifes up to 17 Bits". Game of Life News. Dave Greene. Retrieved on September 17, 2014.
  6. ↑ "18-bit SL Syntheses (100% Complete!)".
  7. ↑ "Colour of a glider". The Life Lexicon. Stephen Silver. Retrieved on April 22, 2009.

External links

Template:LinkWeisstein

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