:galaxy = Kok's galaxy
:Game of Life = Life
:Garden of Eden A configuration of ON and OFF cells that can only occur in generation 0. (This term was first used in connection with cellular automata by John W. Tukey, many years before Life.) It was known from the start that there are Gardens of Eden in Life, because of a theorem by Edward Moore that guarantees their existence in a wide class of cellular automata. Explicit examples have since been constructed, the first by Roger Banks, et al. at MIT in 1971. This example was 9 × 33. In 1974 J. Hardouin-Duparc, et al. produced a 6 × 122 example. The following shows a 14 × 14 example (with 143 ON cells) by Achim Flammenkamp (1991 or 1992).
OO.O.O.O.OO.O. O.OOO.OOO.OO.O OOOO.OOO.OO.O. OOO.O.O.O.OOOO .OOO.O.OOO.OO. OOOOOOO.OOOO.O .O.O.OOOOOOOO. O.OOO.OO.O.O.O OOOOOO.OOOOOO. O.OO.OOOOO.O.O OOO.OOOOOOOOO. .OOO.O.O.O.OOO OOO.O.O.O.OO.O O.OOOOOOOOOOOO
:generation The fundamental unit of time. The starting pattern is generation 0.
:germ (p3) Found by Dave Buckingham, September 1972.
....OO.... .....O.... ...O...... ..O.OOOO.. ..O....O.. .OO.O..... ..O.O.OOOO O.O.O....O OO...OOO.. .......OO.
:gfind A program by David Eppstein used for searching for new spaceships. It was with gfind that Eppstein found the weekender, and Paul Tooke later used it to find the dragon. Compare lifesrc.
:glasses (p2) Compare scrubber and spark coil.
....O........O.... ..OOO........OOO.. .O..............O. .O..OOO....OOO..O. OO.O...O..O...O.OO ...O...OOOO...O... ...O...O..O...O... ....OOO....OOO.... .................. ....OO.O..O.OO.... ....O.OO..OO.O....
:glider (c/4 diagonally, p4) The smallest, most common and first discovered spaceship. This was found by Richard Guy in 1970 while Conway's group was attempting to track the evolution of the R-pentomino. The name is due in part to the fact that it is glide symmetric. (It is often stated that Conway discovered the glider, but he himself has said it was Guy. See also the cryptic reference ("some guy") in Winning Ways.)
OOO O.. .O.The term "glider" is also occasionally (mis)used to mean "spaceship".
:glider-block cycle An infinite oscillator based on the following reaction (a variant of the rephaser). The oscillator consists of copies of this reaction displaced 2n spaces from one another (for some n>6) with blocks added between the copies in order to cause the reaction to occur again halfway through the period. The period of the resulting infinite oscillator is 8n-20. (Alternatively, in a cylindrical universe of width 2n the oscillator just consists of two gliders and two blocks.)
...OO... ...OO... ........ ........ ..O..O.. O.O..O.O .OO..OO.
:glider construction = glider synthesis
:gliderless A gun is said to be gliderless if it does not use gliders. The purist definition would insist that a glider does not appear anywhere, even incidentally. For a long time the only known way to construct LWSS, MWSS and HWSS guns involved gliders, and it was not until April 1996 that Dieter Leithner constructed the first gliderless gun (a p46 LWSS gun). The following diagram shows Leithner's p44 MWSS gun which he discovered in April 1997 (shown with Stephen Silver's May 1998 improvement to the bounding box using a modified eater2). This is the smallest known gliderless gun, and also the smallest known MWSS gun. It is based on an important p44 oscillator discovered by Dave Buckingham in early 1992. (Note that a glider shape appears in this gun for three consecutive generations, but always as part of a larger cluster, so even a purist would regard this gun as gliderless.)
.........OO....OO....OO........................... ........O..O.O....O.O..O.......................... ........OOO..........OOO.......................... ...........OO......OO............................. ..........O..OOOOOO..O............................ ..........OO........OO............................ .................................O................ ...............................OOO................ ..............................O........OOO........ ..............................OO.......O..O....... .........................O.............O.......... ........................O..............O...O...... .........................OO............O.......... ........................O.O.............O.O....... .................................................. .......................O.O.....OOO..............OO ........................O.....O..O...............O OO............OOO.......O......OO...........OO.O.. OO...........O...O..........................OO.OO. .............OO.OO................................ .................................OO.........OO.OO. ..............................OO.............O.O.. .............................................O.O.. ..............................................O... .............OO.OO.............O.O................ OO...........O...O.............OO................. OO............OOO................................. ...........................OO..................... ...........................O.O.................... .............................O.................... .............................OO................... .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. ..........OO........OO............................ ..........O..OOOOOO..O............................ ...........OO......OO............................. ........OOO..........OOO.......................... ........O..O.O....O.O..O.......................... .........OO....OO....OO...........................
:glider pusher An arrangement of a queen bee shuttle and a pentadecathlon that can push the path of a passing glider out by one half-diagonal space. This was found by Dieter Leithner in December 1993 and is shown below. It is useful for constructing complex guns where it may be necessary to produce a number of gliders travelling on close parallel paths. See also edge shooter.
.........OO.............. .........OO.............. ......................... ..........O.............. .........O.O............. .........O.O............. ..........O.............. ......................... ......................... .......OO.O.OO........... .......O.....O........... ........O...O............ .O.......OOO............. ..O...................... OOO...................... ......................... ......................... .................O....O.. ...............OO.OOOO.OO .................O....O..
:gliders by the dozen (stabilizes at time 184) In early references this is usually shown in a larger form whose generation 1 is generation 8 of the form shown here.
OO..O O...O O..OO
:glider synthesis 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 syntheses for all still lifes and known oscillators with at most 14 cells were found by Dave Buckingham.
Perhaps the most interesting glider syntheses are those of spaceships, because these can be used to create corresponding guns. Many of the c/2 spaceships that are based on standard spaceships have been synthesized, mostly by Mark Niemiec. In June 1998 Stephen Silver found syntheses for some of the Corderships (although it was not until July 1999 that Jason Summers built a Cordership gun). All other spaceships (except the glider itself, of course) have so far eluded synthesis. Many of them are space dust.
A 3-glider synthesis of a pentadecathlon is shown in the diagram below. This was found in April 1997 by Heinrich Koenig and came as a surprise, as it was widely assumed that anything using just three gliders would already be known.
......O... ......O.O. ......OO.. .......... OOO....... ..O....... .O.....OO. ........OO .......O..
:glider train A certain puffer that produces two rows of blocks and two backward glider waves. Ten of these were used to make the first breeder.
:glide symmetric Undergoing simultaneous reflection and translation. A glide symmetric spaceship is commonly called a flipper.
:gnome = fox
:GoE = Garden of Eden
:GoL = Game of Life
:Gosper glider gun The first known gun, and indeed the first known finite pattern with unbounded growth, found by Bill Gosper in November 1970. It remains by far the smallest known gun. Gosper has since found other guns, see new gun and the p144 gun shown under factory.
........................O........... ......................O.O........... ............OO......OO............OO ...........O...O....OO............OO OO........O.....O...OO.............. OO........O...O.OO....O.O........... ..........O.....O.......O........... ...........O...O.................... ............OO......................
:gourmet (p32) Found by Dave Buckingham in March 1978. Compare with pi portraitor and popover.
..........OO........ ..........O......... ....OO.OO.O....OO... ..O..O.O.O.....O.... ..OO....O........O.. ................OO.. .................... ................OO.. O.........OOO..O.O.. OOO.......O.O...O... ...O......O.O....OOO ..O.O..............O ..OO................ .................... ..OO................ ..O........O....OO.. ....O.....O.O.O..O.. ...OO....O.OO.OO.... .........O.......... ........OO..........
:grammar A set of rules for connecting components together to make an object such as a spaceship, oscillator or still life.
:grandfather = grandparent
:grandparent A pattern is said to be a grandparent of the pattern it gives rise to after two generations. See also parent.
:Gray counter (p4) Found in 1971. If you look at this in the right way you will see that it cycles through the Gray codes from 0 to 3. Compare with R2D2.
......O...... .....O.O..... ....O.O.O.... .O..O...O..O. O.O.O...O.O.O .O..O...O..O. ....O.O.O.... .....O.O..... ......O......
..OO.... .O..O... .O.O.... OO.O..O. ....OO.O .......O ....OOO. ....O...
:grey counter = Gray counter (This form is erroneous, as Gray is surname, not a colour.)
:grin The following common parent of the block. This name relates to the infamous Cheshire cat. See also pre-block.
O..O .OO.
:growing spaceship An object that moves like a spaceship, except that its front part moves faster than its back part and a wick extends between the two. Put another way, a growing spaceship is a puffer whose output is burning cleanly at a slower rate than the puffer is producing it. Examples include blinker ships and pi ships.
:gull = elevener
:gun Any stationary pattern that emits spaceships (or rakes) forever. For examples see double-barrelled, edge shooter, factory, gliderless, Gosper glider gun, new gun and true.
:gunstar Any of a series of glider guns of period 144+72n (for all non-negative integers n) constructed by Dave Buckingham in 1990 based on his transparent block reaction and Robert Wainwright's p72 oscillator (shown under factory).