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:B = B-heptomino

:B29 (c/4 diagonally, p4) The following spaceship, found by Hartmut Holzwart in April 2004. A glider synthesis of this spaceship was completed by Tanner Jacobi in April 2015.

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

:B-52 bomber The following p104 double-barrelled glider gun. It uses a B-heptomino and emits one glider every 52 generations. It was found by Noam Elkies in March 1996, except that Elkies used blockers instead of molds, the improvement being found by David Bell later the same month.

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

:B60 A Herschel conduit discovered by Michael Simkin in 2015 using his search program, CatForce. It is one of two known Blockic elementary conduits. After 60 ticks, it produces a Herschel rotated 180 degrees at (×,y) relative to the input. It can most easily be connected to another B60 conduit, producing a closed loop, the Simkin glider gun.

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

:babbling brook Any oscillator whose rotor consists of a string of cells each of which is adjacent to exactly two other rotor cells, except for the endpoints which are adjacent to only one other rotor cell. Compare muttering moat. Examples include the beacon, the great on-off, the light bulb and the spark coil. The following less trivial example (by Dean Hickerson, August 1997) is the only one known with more than four cells in its rotor. It is p4 and has a 6-cell rotor.

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

:backrake Another term for a backwards rake. A p8 example by Jason Summers is shown below. See total aperiodic for a p12 example.

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

:backward glider A glider which moves at least partly in the opposite direction to the puffer(s) or spaceship(s) under consideration.

:bait An object in a converter, usually a small still life, that is temporarily destroyed by an incoming signal, but in such a way that a usable output signal is produced. In general such a converter produces multiple output signals (or a signal splitter is added) and one branch of the output is routed to a factory mechanism that rebuilds the bait object so that the converter can be re-used.

:baker (c p4 fuse) A fuse by Keith McClelland.

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

:baker's dozen (p12) A loaf hassled by two blocks and two caterers. The original form (using p4 and p6 oscillators to do the hassling) was found by Robert Wainwright in August 1989.

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

:bakery (p1) A common formation of two bi-loaves.

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

:banana spark A common three-bit polyplet spark used in glider synthesis and signal circuitry. The buckaroo is an oscillator that produces this spark. It can be used to turn a glider 90 degrees:

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

:barberpole Any p2 oscillator in the infinite sequence bipole, tripole, quadpole, pentapole, hexapole, heptapole ... (It wasn't my idea to suddenly change from Latin to Greek.) This sequence of oscillators was found by the MIT group in 1970. The term is also used (usually in the form "barber pole") to describe other extensible sections of oscillators or spaceships, especially those (usually of period 2) in which all generations look alike except for a translation and/or rotation/reflection. Any barberpole can be lengthened by the reaction shown in barbershop. See also pseudo-barberpole.

:barberpole intersection = quad

:barbershop An object created by Jason Summers in 1999 which builds an infinite barberpole. It uses slide guns to repeatedly lengthen a barberpole at a speed of c/124. The key lengthening reaction from Mark Niemiec is shown below:

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

:barber's pole = barberpole

:barge (p1)

	.O..
	O.O.
	.O.O
	..O.

:basic shuttle = queen bee shuttle

:beacon (p2) The third most common oscillator. Found by Conway, March 1970.

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

:beacon maker (c p8 fuse)

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

:beehive (p1) The second most common still life.

	.OO.
	O..O
	.OO.

:beehive and dock (p1)

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

:beehive on big table = beehive and dock

:beehive pusher = hivenudger

:beehive stopper A Spartan logic circuit discovered by Tanner Jacobi on 12 May 2015. It converts an input glider signal into a beehive, in such a way that the beehive can cleanly absorb a single glider from a perpendicular glider stream. The circuit can't be re-used until the beehive "bit" is cleared by the passage of at least one perpendicular input.

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

This term has sometimes been used for the beehive catalyst variant of SW-2, and also for Paul Callahan's larger glider stopper, which also provides optional 0-degree and 180-degree glider outputs.

:beehive wire See lightspeed wire.

:beehive with tail (p1)

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

:Bellman A program for searching catalytic reactions, developed by Mike Playle, which successfully found the Snark.

:belly spark The spark of a MWSS or HWSS other than the tail spark.

:bent keys (p3) Found by Dean Hickerson, August 1989. See also odd keys and short keys.

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

:BFx59H One of the earliest and most remarkable converters, discovered by Dave Buckingham in July 1996. In 59 generations it transforms a B-heptomino into a clean Herschel with very good clearance, allowing easy connections to other conduits. It forms the final stage of many of the known composite conduits, including the majority of the original sixteen Herschel conduits. Here a ghost Herschel marks the output location:

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

:B-heptomino (stabilizes at time 148) This is a very common pattern. It often arises with the cell at top left shifted one space to the left, which does not affect the subsequent evolution. B-heptominoes acquired particular importance in 1996 due to Dave Buckingham's work on B tracks. See in particular My Experience with B-heptominos in Oscillators.

	O.OO
	OOO.
	.O..

:B-heptomino shuttle = twin bees shuttle

:bi-block (p1) The smallest pseudo still life.

	OO.OO
	OO.OO

:bi-block fuse A clean fuse made by a row of bi-blocks separated by 2 cell gaps. The bi-block row wick is usually created by a bi-block puffer. The burning advances 8 cells every 12 generations making its speed 2c/3.

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

:bi-block puffer Any puffer whose output is bi-blocks. The term is particularly used for p8 c/2 puffers, in which case a bi-block fuse is created. A bi-block puffer is easily made using two backrakes whose gliders impact symmetrically. Jason Summers welded two backrakes to form a more compact puffer, as shown below.

	...........O.O............OO..............................
	..........O..O..........O....O............................
	.........OO.......O....O..................................
	........O......OO.O....O.....O............................
	.......OOOOOO..O.......OOOOOO.............................
	....OO.......O...OOOO.....................................
	...O...OOO.O....O.........................................
	..O...O...OO.O..OO.O..O...................................
	..O.....OO...O.....O......................................
	..OOO...OOOO.O.......O.OO.................................
	...........O.........O..O......O..........................
	..OOO......O.O.......O..O....O.O..........................
	.O.....O.....O........OO......OO.....O..OO..OO..OO..OO..OO
	O...OO.O...OO.......................OO..OO..OO..OO..OO..OO
	O...O......OOO............................................
	O...OO.O...OO.......................OO..OO..OO..OO..OO..OO
	.O.....O.....O........OO......OO.....O..OO..OO..OO..OO..OO
	..OOO......O.O.......O..O....O.O..........................
	...........O.........O..O......O..........................
	..OOO...OOOO.O.......O.OO.................................
	..O.....OO...O.....O......................................
	..O...O...OO.O..OO.O..O...................................
	...O...OOO.O....O.........................................
	....OO.......O...OOOO.....................................
	.......OOOOOO..O.......OOOOOO.............................
	........O......OO.O....O.....O............................
	.........OO.......O....O..................................
	..........O..O..........O....O............................
	...........O.O............OO..............................
By periodically burning the bi-block fuse using perturbations by a following backrake and spaceships, c/2 rakes can be created for all periods that are a multiple of eight.

:bi-boat = boat-tie

:biclock The following pure glider generator consisting of two clocks.

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

:big beacon = figure-8

:big fish = HWSS

:big glider (c/4 diagonally, p4) This was found by Dean Hickerson in December 1989 and was the first known diagonal spaceship other than the glider.

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

:big S (p1)

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

:big table = dock

:billiard table = billiard table configuration.

:billiard table configuration Any oscillator in which the rotor is enclosed within the stator. Examples include airforce, cauldron, clock II, Hertz oscillator, negentropy, pinwheel, pressure cooker and scrubber.

:bi-loaf This term has been used in at least three different senses. A bi-loaf can be half a bakery:

	.O.....
	O.O....
	O..O...
	.OO.O..
	...O.O.
	...O..O
	....OO.
or it can be the following much less common still life:
	..O....
	.O.O...
	O..O...
	.OO.OO.
	...O..O
	...O.O.
	....O..
or the following pure glider generator:
	..O.
	.O.O
	O..O
	.OO.
	O..O
	O.O.
	.O..

:bipole (p2) The barberpole of length 2.

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

:bi-pond (p1)

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

:bi-ship = ship-tie

:bit A live cell, if used in reference to still life population. For example, a beehive is a 6-bit still life. Other uses generally involve information storage: a memory cell such as a honey bit that can hold one binary bit of information for later retrieval.

:biting off more than they can chew (p3) Found by Peter Raynham, July 1972.

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

:Black&White = Immigration

:blasting cap The pi-heptomino (after the shape at generation 1). A term used at MIT and still occasionally encountered.

:blinker (p2) The smallest and most common oscillator. Found by Conway, March 1970.

	OOO

:blinker fuse A clean fuse made from a row of blinkers separated by one cell gaps. The blinker row wick is usually created by a blinker puffer. The fuse can burn in at least three different ways at a speed of 2c/3 depending on the method used to ignite the end of the row of blinkers. This variant has found the most use. The burning advances 12 cells every 18 generations.

	....................................................O.
	.............................................OO.O..O.O
	............................................O.O.OOOO.O
	OOO.OOO.OOO.OOO.OOO.OOO.OOO.OOO.OOO.OOO.OOO.O.........
	............................................O.O.OOOO.O
	.............................................OO.O..O.O
	....................................................O.
Fuses can also be made with blinker rows which contain occasional two cell gaps, since the burning reaction is able to bridge those gaps.

:blinker puffer Any puffer whose output is blinkers. However, the term is particularly used for p8 c/2 puffers. The first such blinker puffer was found by Robert Wainwright in 1984, and was unexpectedly simple:

	...O.....
	.O...O...
	O........
	O....O...
	OOOOO....
	.........
	.........
	.........
	.OO......
	OO.OOO...
	.OOOO....
	..OO.....
	.........
	.....OO..
	...O....O
	..O......
	..O.....O
	..OOOOOO.
Since then many more blinker puffers have been found. The following one was found by David Bell in 1992 when he was trying to extend an x66:
	.............OOO.
	............OOOOO
	...........OO.OOO
	............OO...
	.................
	.................
	.........O.O.....
	..O.....O..O.....
	.OOOOO...O.O.....
	OO...OO.OO.......
	.O.......O.......
	..OO..O..O.......
	..........O......
	..OO..O..O.......
	.O.......O.......
	OO...OO.OO.......
	.OOOOO...O.O.....
	..O.....O..O.....
	.........O.O.....
	.................
	.................
	............OO...
	...........OO.OOO
	............OOOOO
	.............OOO.
The importance of this larger blinker puffer (and others like it), is that the engine which produces the blinker output is only p4. The blinker row produced by the puffer can easily be ignited, and the resulting blinker fuse burns cleanly with a speed of 2c/3. When the burning catches up to the engine, it causes a phase change in the puffer. This fact allows p8 blinker puffers to be used to construct rakes of all periods which are large multiples of four.

:blinker pull The following glider/blinker collision, which moves a blinker (-1,3) toward the glider source:

	OOO.
	....
	....
	....
	.OOO
	.O..
	..O.

:blinkers bit pole (p2) Found by Robert Wainwright, June 1977.

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

:blinker ship A growing spaceship in which the wick consists of a line of blinkers. An example by Paul Schick based on his Schick engine is shown below. Here the front part is p12 and moves at c/2, while the back part is p26 and moves at 6c/13. Every 156 generations 13 blinkers are created and 12 are destroyed, so the wick becomes one blinker longer.

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

:block (p1) The most common still life, and also the most common object produced by 2-glider collisions (six different ways).

	OO
	OO
This can be used as a catalyst in many reactions. For examples, it can destroy the beehive produced by the queen bee shuttle and can destroy an evolving honey farm:
	..O.O....
	..OO.....
	...O.....
	.........
	.......OO
	OOO....OO
	..O......
	.O.......

:blockade (p1) A common formation of four blocks. The final form of lumps of muck.

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

:block and dock (p1)

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

:block and glider (stabilizes at time 106)

	OO..
	O.O.
	..OO

:blocker (p8) Found by Robert Wainwright. See also filter.

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

:Blockic Adjective for constellations consisting entirely of blocks. It's possible to arrange blocks in a way that can be triggered by a single glider to produce any glider constructible pattern. A simple example of a Blockic pattern is shown under fuse. See also seed.

:block keeper See keeper.

:block on big table = block and dock

:block on table (p1)

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

:block pull The following glider/block collision, which moves a block (2,1) toward the glider source. Performing this reaction twice using a salvo of two gliders can move a block diagonally back by three cells, which can be of use for a sliding block memory.

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

:block pusher A pattern emitting streams of gliders which can repeatedly push a block further away. This can be used as part of a sliding block memory.

The following pattern, in which three gliders push a block one cell diagonally, is an example of how a block pusher works.

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

A universal construction elbow recipe library is also likely to contain one or more block-pushing reactions, since blocks are commonly used as elbows.

:blom (stabilizes at time 23314) The following methuselah, found by Dean Hickerson in July 2002.

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

:blonk A block or a blinker. This term is mainly used in the context of sparse Life and was coined by Rich Schroeppel in September 1992.

:blonker (p6) The following oscillator, found by Nicolay Beluchenko in April 2004.

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

:boat (p1) The only 5-cell still life.

	OO.
	O.O
	.O.
A boat can be used as a 90-degree one-time turner.

:boat-bit A binary digit represented by the presence of a boat next to a snake (or other suitable object, such as an aircraft carrier). The bit can be toggled by a glider travelling along a certain path. A correctly timed glider on a crossing path can detect whether the transition was from 1 to 0 (in which case the crossing glider is deleted) or from 0 to 1 (in which case it passes unharmed). Three gliders therefore suffice for a non-destructive read. The mechanisms involved are shown in the diagram below. Here the bit is shown in state 0. It is about to be set to 1 and then switched back to 0 again. The first crossing glider will survive, but the second will be destroyed.

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

In January 1997 David Bell found a method of reading the bit while setting it to 0. A MWSS is fired at the boat-bit. If it is already 0 (absent) then the MWSS passes unharmed, but if it is 1 (present) then the boat and the MWSS are destroyed and, with the help of an eater1, converted into a glider which travels back along exactly the same path that is used by the gliders that toggle the boat-bit.

	................................................O........
	................................................OOO......
	...................................................O.....
	..................................................OO.....
	.........................................................
	.........................................................
	.........................................................
	.........................................................
	..O......................................................
	O...O..............................................O.....
	.....O..............................OOOOO...........O....
	O....O.............................O....O.........OOO....
	.OOOOO..................................O................
	...................................O...O.................
	.....................................O...................
	.........................................................
	.........................................................
	.......................................................OO
	........................................................O
	.......................................................O.
	.......................................................OO
There are many other equivalent methods based on alternate incoming test signals.

:boat maker (c p4 fuse)

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

:boat on boat = boat-tie

:boat-ship-tie = ship tie boat

:boatstretcher See tubstretcher.

:boat-tie (p1) A 10-cell still life consisting of two boats placed tip-to-tip. The name is a pun on "bow tie".

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

:bobsled = switch engine channel.

:boojum reflector (p1) Dave Greene's name for the following 180-degree glider reflector which he found in April 2001, winning $100 bounties offered by Alan Hensel and Dieter Leithner. The name is taken from Lewis Carroll's _The Hunting of the Snark_, referring to the fact that a small 90-degree stable reflector was really what was wanted. 180-degree reflectors are relatively undesirable and have limited use in larger circuitry constructions.

The boojum reflector was the smallest and fastest known stable reflector until the discovery of the rectifier in 2009, followed by the Snark in 2013.

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

:bookend The following induction coil. It is generation 1 of century.

	..OO
	O..O
	OOO.

:bookends (p1)

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

:boss (p4) Found by Dave Buckingham, 1972.

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

:bottle (p8) Found by Achim Flammenkamp in August 1994. The name is a back-formation from ship in a bottle.

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

:bounding box The smallest rectangular array of cells that contains the whole of a given pattern. For oscillators and guns this usually is meant to include all phases of the pattern, but in the case of guns, the outgoing stream(s) are excluded. The bounding box is one of the standard ways to measure the size of an object; the other standard metric is the population.

:bow tie = boat-tie

:brain (c/3 orthogonally, p3) Found by David Bell, May 1992.

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

:branching spaceship An extensible spaceship containing components which can be attached in multiple ways so that the result can contain arbitrarily many arms arranged like a binary tree. Here is an example of a period 2 c/2 branching spaceship, which also includes a wicktrailer:

	.....................O.................O......................
	....................OOO...............OOO.....................
	..................OO.OOO.............OOO.OO...................
	...................O..O.OO....O....OO.O..O....................
	................OO.O....O.O.OO.OO.O.O....O.OO.................
	................OO.O.O..O.O.......O.O..O.O.OO.................
	................O........OOO.O.O.OOO........O....OOO..........
	...............OO.......OO.........OO.......OO..O...O.........
	...............O...............................O....OO........
	........OOO....OOOO.........................OOOO..OO.O........
	.......O...O..OO..OO..........................O.O....OO.......
	......OO....O......O....OOO.........................O.........
	......O.OO..OOOO...OO..O...O..........................OOO.....
	.....OO....O.O........O....OO...........................OO....
	.......O...........OOOO..OO.O............................O....
	...OOO...............O.O....OO...........................OO...
	..OO.......................O..................................
	..O..........................OOO..............................
	.OO............................OO.............................
	.O..............................O....OOO......................
	.OOOO...........................OO..O...O.....................
	OO..OO.............................O....OO....................
	.....O....OOO...................OOOO..OO.O....................
	.....OO..O...O....................O.O....OO...................
	........O....OO.........................O.....................
	.....OOOO..OO.O...........................OOO.................
	.......O.O....OO............................OO................
	.............O...............................O................
	...............OOO...........................OO...............
	.................OO...........................O...............
	..................O........................OOOO....OOO........
	..................OO......................OO..OO..O...O.......
	...................O...............OOO....O......O....OO......
	................OOOO..............O...O..OO...OOOO..OO.O......
	...............OO..OO............OO....O........O.O....OO.....
	...............O.................O.OO..OOOO...........O.......
	..............OO................OO....O.O...............OOO...
	..............O...................O.......................OO..
	..............OOOO............OOO..........................O..
	.............OO..OO..........OO............................OO.
	..................O..........O..............................O.
	..................OO........OO...........................OOOO.
	...................O........O...........................OO..OO
	................OOOO........OOOO........................O.....
	...............OO..OO......OO..OO......................OO.....
	...............O................O......................O......
	..............OO................OO.....................OOOO...
	..............O.......................................OO..OO..
	..............OOOO.........................................O..
	.............OO..OO........................................OO.
	..................O...........................................
	..................OO..........................................
Branching spaceships have also been constructed for other speeds, such as c/3.

:breeder Any pattern whose population grows at a quadratic rate, although it is usual to exclude spacefillers. It is easy to see that this is the fastest possible growth rate.

The term is also sometimes used to mean specifically the breeder created by Bill Gosper's group at MIT, which was the first known pattern exhibiting superlinear growth.

There are four common types of breeder, known as MMM, MMS, MSM and SMM (where M=moving and S=stationary). Typically an MMM breeder is a rake puffer, an MMS breeder is a puffer producing puffers which produce stationary objects (still lifes and/or oscillators), an MSM breeder is a gun puffer and an SMM breeder is a rake gun. There are, however, less obvious variants of these types. Other less common breeder categories (SSS, hybrid MSS/MSM, etc.) can be created with some difficulty, based on universal constructor technology; see Pianola breeder.

The original breeder was of type MSM (a p64 puffer puffing p30 glider guns). The known breeder with the smallest initial population is switch-engine ping-pong.

:bridge A term used in naming certain still lifes (and the stator part of certain oscillators). It indicates that the object consists of two smaller objects joined edge to edge, as in snake bridge snake.

:broken lines A pattern constructed by Dean Hickerson in May 2005 which produces complex broken lines of gliders and blocks.

:broth = soup

:BRx46B A Spartan elementary conduit discovered by Michael Simkin on 25 April 2016, one of the relatively few known conduits that can move a B-heptomino input to a B-heptomino output without an intervening Herschel stage.

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

:BTC = billiard table configuration

:B track A track for B-heptominoes. A B-heptomino becomes a Herschel plus a block in twenty generations, so this term was nearly synonymous with Herschel track until the discovery of elementary conduits that convert a B directly to another B, or to some other non-Herschel signal output. See for example BRx46B.

:buckaroo (p30) A queen bee shuttle stabilized at one end by an eater in such a way that it can turn a glider, as shown below. The glider turning reaction uses a banana spark and is colour-preserving. The mechanism was found by Dave Buckingham in the 1970s. The name is due to Bill Gosper. .

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

:bullet heptomino Generation 1 of the T-tetromino.

	.O.
	OOO
	OOO

:bumper A periodic colour-preserving glider reflector discovered by Tanner Jacobi on 6 April 2016. See p4 bumper, p5 bumper, p6 bumper, p7 bumper, p8 bumper, p9 bumper, p15 bumper, and p22 bumper.

:bun The following induction coil. By itself this is a common predecessor of the honey farm. See also cis-mirrored R-bee.

	.OO.
	O..O
	.OOO

:bunnies (stabilizes at time 17332) This is a parent of rabbits and was found independently by Robert Wainwright and Andrew Trevorrow.

	O.....O.
	..O...O.
	..O..O.O
	.O.O....

:burloaf = loaf

:burloaferimeter (p7) Found by Dave Buckingham in 1972. See also airforce.

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

:burn A reaction which travels indefinitely as a wave through the components of a wick or an agar. A burning wick is known as a fuse.

If the object being burned has a spatial periodocity, then the active area of the burning usually remains bounded and so eventually develops a periodicity too. It is unknown whether this will always occur.

The speed of burning can range from arbitrarily slow up to the speed of light. The results of burning can be clean (leaving no debris), or leaving debris usually much different from the original object. In rare cases, a reburnable fuse produces an exact copy of the original object, allowing the creation of objects such as the telegraph.

In many useful cases burning can be initiated by impacting an object with gliders or other spaceships. An object might be able to burn in more than one way, depending on how the burn is initiated.

:bushing That part of the stator of an oscillator which is adjacent to the rotor. Compare casing.

:butterfly The following pattern, or the formation of two beehives that it evolves into after 33 generations. (Compare teardrop, where the beehives are five cells closer together.)

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

:Bx125 An elementary conduit, one of the original sixteen Herschel conduits, discovered by Paul Callahan in November 1998. After 125 ticks, it produces an inverted Herschel rotated 180 degrees at (-9, -17) relative to the input. Its recovery time is 166 ticks. A ghost Herschel in the pattern below marks the output location:

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

:Bx222 A composite conduit, one of the original sixteen Herschel conduits, discovered by Paul Callahan in October 1998. It is made up of three elementary conduits, HF95P + PB68B + BFx59H. After 222 ticks, it produces a backward-traveling inverted Herschel at (6, -16) relative to the input. Its recovery time is 271 ticks. A ghost Herschel in the pattern below marks the output location:

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

:by flops (p2) Found by Robert Wainwright.

	...O..
	.O.O..
	.....O
	OOOOO.
	.....O
	.O.O..
	...O..

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