Life Lexicon (A)
Author: Stephen A. Silver
Description: Part of Stephen Silver's Life Lexicon.

Introduction | Bibliography

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:Achim's p144 (p144) This was found (minus the blocks shown below) on a cylinder of width 22 by Achim Flammenkamp in July 1994. Dean Hickerson reduced it to a finite form using figure-8s the same day. The neater finite form shown here - replacing the figure-8s with blocks - was found by David Bell in August 1994. See factory for a use of this oscillator.

    OO........................OO
    OO........................OO
    ..................OO........
    .................O..O.......
    ..................OO........
    ..............O.............
    .............O.O............
    ............O...O...........
    ............O..O............
    ............................
    ............O..O............
    ...........O...O............
    ............O.O.............
    .............O..............
    ........OO..................
    .......O..O.................
    ........OO..................
    OO........................OO
    OO........................OO

:Achim's p16 (p16) Found by Achim Flammenkamp, July 1994.

    .......OO....
    .......O.O...
    ..O....O.OO..
    .OO.....O....
    O..O.........
    OOO..........
    .............
    ..........OOO
    .........O..O
    ....O.....OO.
    ..OO.O....O..
    ...O.O.......
    ....OO.......

:Achim's p4 (p4) Dave Buckingham found this in a less compact form (using two halves of sombreros) in 1976. The form shown here was found by Achim Flammenkamp in 1988. The rotor is two copies of the rotor of 1-2-3-4, so the oscillator is sometimes called the "dual 1-2-3-4".

    ..OO...OO..
    .O..O.O..O.
    .O.OO.OO.O.
    OO.......OO
    ..O.O.O.O..
    OO.......OO
    .O.OO.OO.O.
    .O..O.O..O.
    ..OO...OO..

:Achim's p5 = pseudo-barberpole

:Achim's p8 (p8) Found by Achim Flammenkamp, July 1994.

    .OO......
    O........
    .O...O...
    .O...OO..
    ...O.O...
    ..OO...O.
    ...O...O.
    ........O
    ......OO.

:acorn (stabilizes at time 5206) A methuselah found by Charles Corderman.

    .O.....
    ...O...
    OO..OOO

:A for all (p6) Found by Dean Hickerson in March 1993.

    ....OO....
    ...O..O...
    ...OOOO...
    .O.O..O.O.
    O........O
    O........O
    .O.O..O.O.
    ...OOOO...
    ...O..O...
    ....OO....

:against-the-grain grey ship A grey ship in which the region of density 1/2 consists of lines of ON cells lying perpendicular to the direction in which the spaceship moves. See also with-the-grain grey ship.

:agar Any pattern covering the whole plane that is periodic in both space and time. The simplest (nonempty) agar is the stable one extended by the known spacefillers. For some more examples see chicken wire, houndstooth agar, onion rings, squaredance and Venetian blinds. Tiling the plane with the pattern `O......O` produces another interesting example: a p6 agar which has a phase of density 3/4, which is the highest yet obtained for any phase of an oscillating pattern.

:aircraft carrier (p1) This is the smallest still life that has more than one island.

    OO..
    O..O
    ..OO

:airforce (p7) Found by Dave Buckingham in 1972. The rotor consists of two copies of that used in the burloaferimeter.

    .......O......
    ......O.O.....
    .......O......
    ..............
    .....OOOOO....
    ....O.....O.OO
    ...O.OO...O.OO
    ...O.O..O.O...
    OO.O...OO.O...
    OO.O.....O....
    ....OOOOO.....
    ..............
    ......O.......
    .....O.O......
    ......O.......

:AK47 reaction The following reaction (found by Rich Schroeppel and Dave Buckingham) in which a honey farm predecessor, catalysed by an eater and a block, reappears at another location 47 generations later, having produced a glider and a traffic light. This is the basis of a very small (but pseudo) p94 glider gun found by Paul Callahan in July 1994, and was in 1990 the basis for the Dean Hickerson's construction of the first true p94 gun. (This latter gun was enormous, and has now been superseded by comparatively small Herschel loop guns.)

    .....O....
    ....O.O...
    ...O...O..
    ...O...O..
    ...O...O..
    ....O.O...
    .....O....
    ..........
    ..OO......
    ...O......
    OOO.....OO
    O.......OO

:Al Jolson = Jolson

:almosymmetric (p2) Found in 1971.

    ....O....
    OO..O.O..
    O.O......
    .......OO
    .O.......
    O......O.
    OO.O.O...
    .....O...

:anteater A pattern that consumes ants.

:antlers = moose antlers

:ants (p5 wick) The standard form is shown below. It is also possible for any ant to be displaced by one or two cells relative to either or both of its neighbouring ants. Dean Hickerson found fenceposts for both ends of this wick in October 1992 and February 1993. See electric fence, and also wickstretcher.

    OO...OO...OO...OO...OO...OO...OO...OO...OO..
    ..OO...OO...OO...OO...OO...OO...OO...OO...OO
    ..OO...OO...OO...OO...OO...OO...OO...OO...OO
    OO...OO...OO...OO...OO...OO...OO...OO...OO..

:antstretcher Any wickstretcher that stretches ants.

:anvil The following induction coil.

    .OOOO.
    O....O
    .OOO.O
    ...O.OO

:APPS (c/5 orthogonally, p30) An asymmetric PPS. The same as the SPPS, but with the two halves 15 generations out of phase with one another. Found by Alan Hensel in May 1998.

:ark A pair of mutually stabilizing switch engines. The archetype is Noah's ark. The diagram below shows an ark found by Nick Gotts that takes until generation 736692 to stabilize, and can therefore be considered as a methuselah.

    ...........................O....
    ............................O...
    .............................O..
    ............................O...
    ...........................O....
    .............................OOO
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    ................................
    OO..............................
    ..O.............................
    ..O.............................
    ...OOOO.........................

:arm A long extension hanging off from the main body of a spaceship or puffer perpendicular to the direction of travel.

A lot of known spaceships have multiple arms. This is an artefact of the search methods used to find such spaceships, rather than an indication of what a "typical" spaceship might look like.

:ash The (stable or oscillating) debris left by a random reaction. Experiments show that for random soups with moderate initial densities (say 0.25 to 0.5) the resulting ash has a density of about 0.0287. (This is, of course, based on what happens in finite fields. In infinite fields the situation may conceivably be different in the long run because of the effect of certain initially very rare objects such as replicators.)

:aVerage (p5) Found by Dave Buckingham, 1973. The average number of live rotor cells is five (V), which is also the period.

    ...OO........
    ....OOO......
    ..O....O.....
    .O.OOOO.O....
    .O.O....O..O.
    OO.OOO..O.O.O
    .O.O....O..O.
    .O.OOOO.O....
    ..O....O.....
    ....OOO......
    ...OO........

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