lexicon.txt

成功再现康韦的生命游戏。这是人工生命方法的缘起之作

	..*.*..
	*.*.*.*
	**...**

:density:  The density of a pattern is the limit of the proportion of
   live cells in a (2n+1)x(2n+1) square centred on a particular cell as
   n tends to infinity, when this limit exists.  (Note that it does not
   make any difference what cell is chosen as the centre cell.  Also
   note that if the pattern is finite then the density is zero.)  There
   are other definitions of density, but this one will do here.
     In 1994 Noam Elkies proved that the maximum density of a stable
   pattern is 1/2, which had been the conjectured value.  See the paper
   listed in the bibliography.  Marcus Moore provided a simpler proof
   in 1995, and in fact proves that a {still life} with an m x n
   {bounding box} has at most (mn+m+n)/2 cells.
     But what is the maximum average density of an oscillating pattern?
   The answer is conjectured to be 1/2 again, but this remains unproved.
   The best upper bound so far obtained is 8/13 (Hartmut Holzwart,
   September 1992).
     The maximum possible density for a phase of an oscillating pattern
   is also unknown.  An example with a density of 3/4 is known (see
   {agar}), but densities arbitrarily close to 1 may perhaps be
   possible.

:D-heptomino: = {Herschel}

:diamond: = {tub}

:diamond ring: (p3)  Found by Dave Buckingham in 1972.
	......*......
	.....*.*.....
	....*.*.*....
	....*...*....
	..**..*..**..
	.*....*....*.
	*.*.**.**.*.*
	.*....*....*.
	..**..*..**..
	....*...*....
	....*.*.*....
	.....*.*.....
	......*......

:diehard:  Any pattern that vanishes, but only after a long time.  The
   following example vanishes in 130 generations, which is probably the
   limit for patterns of 7 or fewer cells.  Note that there is no limit
   for higher numbers of cells - e.g., for 8 cells we could have a
   glider heading towards an arbitrarily distant blinker.
	......*.
	**......
	.*...***

:dinner table: (p12)  Found by Robert Wainwright in 1972.
	.*...........
	.***.......**
	....*......*.
	...**....*.*.
	.........**..
	.............
	.....***.....
	.....***.....
	..**.........
	.*.*....**...
	.*......*....
	**.......***.
	...........*.

:dirty:  Opposite of {clean}.  A reaction which produces a large amount
   of complicated junk which is difficult to control or use is said
   to be dirty.  Many basic {puffer engine}s are dirty and need to
   be {tame}d by accompanying {spaceship}s in order to produce clean
   output.

:diuresis: (p90)  Found by David Eppstein in October 1998.  His original
   stabilization used {pentadecathlon}s.  The stabilization with
   complicated {still life}s shown here (in two slightly different
   forms) was found by Dean Hickerson the following day.  The name is
   due to Bill Gosper (see {kidney}).
	.....**................**....
	......*................*.....
	......*.*............*.*.....
	.......**............**......
	.............................
	....**..................**...
	....*.*..........**....*.*...
	.....*..........*.*.....*....
	..*.............**.........*.
	..******........*.....******.
	.......*..............*......
	....**..................**...
	....*....................*...
	.....*..................*....
	..***..*..............*..***.
	..*..***........*.....***...*
	...*............**.......***.
	....**..........*.*.....*....
	......*..........**....*..**.
	....**..................**.*.
	.*..*....................*...
	*.*.*..**............**..*...
	.*..*.*.*............*.*.**..
	....*.*................*..*..
	.....**................**....

:dock:  The following {induction coil}.
	.****.
	*....*
	**..**

:domino:  The 2-cell {polyomino}.  A number of objects, such as the
   {HWSS} and {pentadecathlon}, produce domino {spark}s.

:double-barrelled:  Of a {gun}, emitting two streams of {spaceship}s
   (or {rake}s).  See {B-52 bomber} for an example.

:double block reaction:  A certain reaction that can be used to
   stabilize the {twin bees shuttle} (qv).  This was discovered by
   David Bell in October 1996.
     The same reaction sometimes works in other situations, as shown in
   the following diagram where a pair of blocks eats an {R-pentomino}
   and a {LWSS}.  (The LWSS version was known at least as early 1994,
   when Paul Callahan saw it form spontaneously as a result of firing
   a LWSS stream at some random junk.)
	.****.....**....
	*...*......**.**
	....*......*..**
	*..*............
	................
	.............**.
	.............**.

:double caterer: (p3)  Found by Dean Hickerson, October 1989.  Compare
   {caterer} and {triple caterer}.
	.....**...*........
	....*..*..***......
	....**.*.....*.....
	......*.****.*.....
	..***.*.*...*.**...
	.*..*..*...*..*.*..
	*.*..*...*.**....*.
	.*..........**.***.
	..**.**.**...*.....
	...*...*.....*.***.
	...*...*......**..*
	.................**

:double ewe: (p3)  Found by Robert Wainwright before September 1971.
	......**............
	.......*............
	......*.............
	......**............
	.........**.........
	......***.*.........
	*.**.*..............
	**.*.*..............
	.....*...*..........
	....*...**....**....
	....**....**...*....
	..........*...*.....
	..............*.*.**
	..............*.**.*
	.........*.***......
	.........**.........
	............**......
	.............*......
	............*.......
	............**......

:double wing: = {moose antlers}

:dove:  The following {induction coil}.
	.**..
	*..*.
	.*..*
	..***

:down boat with tail: = {cis-boat with tail}

:dragon: (c/6 orthogonally, p6)  This {spaceship}, discovered by
   Paul Tooke in April 2000, was the first known c/6 spaceship.
   All other known c/6 spaceships are {flotilla}s involving at
   least two dragons.
	.............*..**......*..***
	.....*...****.******....*..***
	.*****....*....*....***.......
	*......**.*......**.***..*.***
	.*****.***........****...*.***
	.....*..*..............*......
	........**..........**.**.....
	........**..........**.**.....
	.....*..*..............*......
	.*****.***........****...*.***
	*......**.*......**.***..*.***
	.*****....*....*....***.......
	.....*...****.******....*..***
	.............*..**......*..***

:drain trap: = {paperclip}

:drifter:  A perturbation moving within a stable pattern.  Dean
   Hickerson has written a program to search for drifters, with the
   hope of finding one which could be moved around a track.  Because
   drifters can be very small, they could be packed more tightly than
   {Herschel}s, and so allow the creation of {oscillator}s of periods
   not yet attained, and possibly prove that Life is {omniperiodic}.
   Hickerson has found a number of components towards this end, but
   it has proved difficult to change the direction of movement of a
   drifter, and so far no complete track has been found.  However,
   Hickerson has had success using the same search program to find
   {eater}s with novel properties, such as that used in {diuresis}.

:dual 1-2-3-4: = {Achim's p4}

:early universe:  Conway's somewhat confusing term for {sparse Life}.

:eater:  Any {still life} that has the ability to interact with certain
   patterns without suffering any permanent damage.  (If it doesn't
   suffer even temporary damage then it may be referred to as a {rock}.)
   The {eater1} is a very common eater, and the term "eater" is often
   used specifically for this object.  Other eaters include {eater2},
   {eater3}, {eater4} and even the humble {block}.  (In fact the block
   was the first known eater, being found capable of eating beehives
   from a {queen bee}.)  Another useful eater is shown below, feasting
   on a glider.
	...*.....
	...*.*...
	...**....
	.........
	.......**
	...*...**
	..*.*....
	.*.*.....
	.*.......
	**.......

:eater1: (p1)  Usually simply called an {eater}, and also called a
   fishhook.  Its ability to eat various objects was discovered by
   Bill Gosper in 1971.
	**..
	*.*.
	..*.
	..**

:eater2: (p1)  This {eater} was found by Dave Buckingham in the 1970s.
   Mostly it works like the ordinary eater (see {eater1}) but with two
   slight differences that make it useful despite its size: it takes
   longer to recover from each bite and it acts like an eater in two
   directions.  The first property means that, among other things, it
   can eat a {glider} in a position that would destroy a fishhook.  This
   novel glider-eating action is occasionally of use in itself, and
   combined with the symmetry means that an eater2 can eat gliders along
   four different paths.  An eater2 variant noticed by Stephen Silver in
   May 1998 that is useful for obtaining smaller {bounding box}es can be
   seen under {gliderless}.
	...*.**
	.***.**
	*......
	.***.**
	...*.*.
	...*.*.
	....*..

:eater3: (p1)  This large symmetric {eater}, found by Dave Buckingham,
   has a very different eating action from the {eater1} and {eater2}.
   The {loaf} can take bites out things, being flipped over in the
   process.  The rest of the object merely flips it back again.
	.........**.
	....**..*..*
	.*..*....*.*
	*.*.*.....*.
	.*..*.**....
	....*..*....
	.....*....*.
	......*****.
	............
	........*...
	.......*.*..
	........*...

:eater4: (p1)  Another {eater} by Dave Buckingham, which he found in
   1971, but did not recognize as an eater until 1975 or 1976.  It
   can't eat {glider}s, but it can be used for various other purposes.
   The four NE-most centre cells regrow in a few generations after being
   destroyed by taking a bite out of something.
	...**.........
	...*..........
	**.*..........
	*..**.........
	.**....*......
	...*****......
	...*....**....
	....**..*.....
	......*.*.....
	......*.*.*..*
	.......**.****
	.........*....
	.........*.*..
	..........**..

:eater/block frob: (p4)  Found by Dave Buckingham in 1976 or earlier.
	.**.......
	..*.......
	..*.*.....
	...*.*....
	.....**.**
	........**
	..**......
	...*......
	***.......
	*.........

:eater-bound pond: (p3)  Found by Peter Raynham, July 1972.
	*...........
	***.........
	...*........
	..**........
	...**.......
	....**......
	...*..*.....
	...*..**....
	....**.***..
	........*.*.
	..........*.
	..........**

:eater-bound Z-hexomino: = {pentoad}

:eater eating eater: = {two eaters}

:eater plug: (p2)  Found by Robert Wainwright, February 1973.
	.......*
	.....***
	....*...
	.....*..
	..*..*..
	.*.**...
	.*......
	**......

:eaters +: = {French kiss}

:eaters plus: = {French kiss}

:ecologist: (c/2 orthogonally, p20)  This consists of the classic
   {puffer train} with a {LWSS} added to suppress the debris.  See
   also {space rake}.
	****.....**........
	*...*...**.**......
	*........****......
	.*..*.....**.......
	...................
	.....*.........**..
	...***........*****
	..*...*.....*....**
	..*....*****.....**
	..**.*.****....**..
	....*...**.***.....
	.....*.*...........
	...................
	...................
	****...............
	*...*..............
	*..................
	.*..*..............

:edge-repair spaceship: (c/3 orthogonally, p3)  Any of a family of
   {spaceship}s whose left-hand edge can be used to {perturb} things,
   since it can often repair damage done to itself.  Below are shown
   the two smallest and most useful members of this family, both found
   by David Bell in 1992.  The usefulness of the edge-repair property
   wasn't recognised until July 1997.
	..................................*.....
	........*.......................***.***.
	.......****....................**......*
	..*...*...**.**...........*...*..*...**.
	.****.....*..**..........****...........
	*...*.......*..*........*...*...........
	.*.*..*..................*.*..*.........
	.....*.......................*..........
   The following diagram (showing an edge-repair spaceship deleting a
   {Herschel}) demonstrates the self-repairing action.
	................*.......
	*..............****.....
	*.*.......*...*...**.**.
	***......****.....*..**.
	..*.....*...*.......*..*
	.........*.*..*.........
	.............*..........

:edge shooter:  A {gun} which fires its gliders (or whatever) right
   at the edge of the pattern, so that it can be used to fire them
   closely parallel to others.  This is useful for constructing
   complex guns.  Compare {glider pusher}, which can in fact be used
   for making edge shooters.
     The following diagram shows a p46 edge shooter found by Paul
   Callahan in June 1994.
	**............**..*....**..**.............
	**............*.**......**.**.............
	...............*......*.*.................
	...............***....**..................
	..........................................
	...............***....**..................
	...............*......*.*.................
	**............*.**......**................
	**............**..*....**.................
	..........................................
	..........................................
	..........................................
	..........................................
	..........................................
	..........................................
	...............................***...***..
	..............................*...*.*...*.
	.............................*...**.**...*
	.............................*.**.....**.*
	...............................*.......*..
	..........................................
	..........................................
	..........................................
	..........................................
	..........................................
	..........................................
	..........................................
	..........................................
	..........................................
	..........................................
	...............................**.....**..
	...............................**.....**..

:ed