A '''line puffer''' is a [[puffer]] which produces its output by means of an orthogonal line of cells perpendicular to the direction of travel. The archetypal line puffer was found by [[Alan Hensel]] in March {{year|1994}}, based on a [[spaceship]] found earlier that month by [[Hartmut Holzwart]]. The following month Holzwart found a way to make [[extensible]] [[c/2]] line puffers, and Hensel found a much smaller stabilization the following day. But in October {{year|1995}} [[Tim Coe]] discovered that for large widths these were often unstable, although typically lasting millions of [[generation]]s. In May {{year|1996}}, however, Coe found a way to fix the instability.<ref name="coe">{{CiteGollyPatternCollection|line-puffer-superstable.rle}}</ref> The resulting puffers appear to be completely stable and to exhibit an exponential increase in [[period]] as a function of width, although neither of these things has been proved.
A '''line puffer''' is a [[puffer]] which produces its output by means of an orthogonal line of cells perpendicular to the direction of travel. The archetypal line puffer was found by [[Alan Hensel]] in March {{year|1994}}, based on a [[spaceship]] found earlier that month by [[Hartmut Holzwart]]. The following month Holzwart found a way to make [[extensible]] [[c/2]] line puffers, and Hensel found a much smaller stabilization the following day. But in October {{year|1995}} [[Tim Coe]] discovered that for large widths these were often unstable, although typically lasting millions of [[generation]]s. In May {{year|1996}}, however, Coe found a way to fix the instability.<ref name="coe">{{CiteGollyPatternCollection|line-puffer-superstable.rle}}</ref> The resulting puffers appear to be completely stable and to exhibit an exponential increase in [[period]] as a function of width, although neither of these things has been proved.
Line puffers have enabled the construction of various difficult periods for c/2 spaceships and puffers, including occasionally periods which are not multiples of 4 and which would therefore be impossible to attain with the usual type of construction based on standard spaceships. (See [[frothing puffer]] for another method of constructing such periods.) In particular, the first c/2 [[rake]] with period not divisible by 4 was achieved in January {{year|2000}} when [[David Bell]] constructed a p42 [[backrake]] by means of line puffers.<ref name="bell">{{CiteSummersPattern|name=jslife}}</ref>
Line puffers have enabled the construction of various difficult periods for c/2 spaceships and puffers, including occasionally periods which are not multiples of 4 and which would therefore be impossible to attain with the usual type of construction based on standard spaceships. (See [[frothing puffer]] for another method of constructing such periods.) In particular, the first c/2 [[rake]] with period not divisible by 4 was achieved in January {{year|2000}} when [[David Bell]] constructed a p42 forward [[rake]] by means of line puffers.<ref name="bell">{{CiteSummersPattern|name=jslife}}</ref>
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Revision as of 18:07, 19 April 2023
A line puffer is a puffer which produces its output by means of an orthogonal line of cells perpendicular to the direction of travel. The archetypal line puffer was found by Alan Hensel in March 1994, based on a spaceship found earlier that month by Hartmut Holzwart. The following month Holzwart found a way to make extensiblec/2 line puffers, and Hensel found a much smaller stabilization the following day. But in October 1995Tim Coe discovered that for large widths these were often unstable, although typically lasting millions of generations. In May 1996, however, Coe found a way to fix the instability.[1] The resulting puffers appear to be completely stable and to exhibit an exponential increase in period as a function of width, although neither of these things has been proved.
Line puffers have enabled the construction of various difficult periods for c/2 spaceships and puffers, including occasionally periods which are not multiples of 4 and which would therefore be impossible to attain with the usual type of construction based on standard spaceships. (See frothing puffer for another method of constructing such periods.) In particular, the first c/2 rake with period not divisible by 4 was achieved in January 2000 when David Bell constructed a p42 forward rake by means of line puffers.[2]