Parallel HBK

Half-bakery knightship
Half-bakery knightship image
View static image
Pattern type	Spaceship
Number of cells	132945
Bounding box	31080 × 32771
Direction	slope 2
Period	245912
Mod	Unknown
Speed	(6,3)c/245912 | Unknown
Heat	Unknown
Discovered by	Chris Cain
Year of discovery	2014
Rules Outer-totalistic rules B3/S23 only # of rules 20 = 1

Half-bakery knightship is a class of knightships based on the well-known half-bakery reaction with a glider. As of 2014, representatives of this class are the smallest known oblique spaceships in Conway's Game of Life both in terms of the bounding box and minimum population. The Gemini and its derivatives, the only formerly known oblique spaceships, step farther in each period in spite of their larger size and population, and so can travel much faster than half-bakery knightships.

In May 2014 Ivan Fomichev found the key reactions, which allow long chains of half-bakeries to regenerate themselves at (6, 3), and also to regenerate seed constellations at one end of the ship. When triggered, the seeds produce the small glider salvos that mediate the (6, 3) offset reaction. Components and slow salvo syntheses for the ship were found by the combined efforts of Chris Cain, Ivan Fomichev and Dave Greene.

Adam P. Goucher proposed the base design for the ship, and in July 2014 wrote a Golly script that assembled the components into an unoptomized but working "half-baked knightship" of any sufficiently large period. Several days later, Chris Cain wrote an alternative assembly script that built a half-bakery knightship an order of magnitude smaller, using a more complex design with the most efficient known components.

Chris Cain's design allows for several slow-salvo construction recipes to be completed in parallel, whereas the first half-baked knightship did all constructions serially.

Like the (2,1) self-reconstructor, this knightship moves very slowly, but unlike a self-reconstructor, only a tiny fraction of the half-bakery knightship has an embedded construction recipe. The half-bakery chains encode a small slow salvo recipe, but the positions of the half-bakeries are not encoded anywhere else.

See also

• Caterpillar
• Gemini