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2014 May 23

Glider Constructions
Constructions Known for All Still Lifes up to 18 Bits

17-bit still life index pattern
Index pattern showing the 298 remaining 17-bit
still lifes that were not trivially synthesizable
as of January 2014.
A project to find glider syntheses for all stable objects up to 16 bits was completed at the beginning of 2014. Since then, an impressive five-month collaborative effort mostly between Martin Grant, Mark Niemiec, and Matthias Merzenich has produced new syntheses for about three hundred "non-trivial" 17-bit still lifes. There has been more progress in solving glider-synthesis problems in the last year than in the entire preceding decade, according to Mark's description of the recent surge of activity. The image at right links to a forum posting with the original index pattern.

synthesis of 17-bit still life #131 from the index pattern
Complete synthesis of still life #131 from the index pattern, consisting of
26 construction stages. Each stage is an intermediate still life that is
slightly more difficult to construct than the previous stage.
At right is a sample synthesis for one of the non-trivial 17-bit still lifes, #131 in the index pattern above.

Incremental synthesis of 17-bit still life #248 from the index pattern
Incremental synthesis of still life #248 from the
index pattern, with 9 construction stages.
Most commonly, glider syntheses are shown in incremental stages, with a separate stage for each grouping of gliders that must be precisely synchronized with each other.

UPDATE: Several hundred 18-bit still lifes were synthesized between June and November 2014, resulting in known syntheses for all gliders up to 18 bits.