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x = 13, y = 19, rule = B3/S23 b2o6b2o$o2bo4bo2bo$o2bo4bo2bo$o2bo4bo2bo$b2o6b2o3$7bo$5bo2bob2o$6b2o2b 2o3$6b4o$5b6o$4b8o$3b2o6b2o$4b8o$5b6o$6b4o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ GPS 3 ZOOM 12 LOOP 15 ]]
Pattern type Oscillator
Number of cells 42
Bounding box 18×22
Period 15
Mod 15
Heat 47.9
Volatility 0.98
Strict volatility 0.98
Discovered by Robert Wainwright
Year of discovery 1984

Jolson (also known as Al Jolson[note 1]) is a period-15 oscillator consisting of two blocks hassled by two pentadecathlons. It was found by Robert Wainwright in November 1984 and named by Bill Gosper.

The hassling mechanism requires two domino sparks, constantly 3 generations apart, provided by sparkers of period 9 or above (e.g. Merzenich's p31). A period 9 version that uses two snackers is possible (see below), but p14 (with tetradecathlons) is impossible.[1]

Image gallery

The period 9 version of Jolson
Download RLE: click here
One of the phases of Jolson, which led to its name


  1. The name is a reference to Al Jolson, a famous American singer.


  1. Mark Niemiec (August 14, 2019). Re: Oscillator Discussion Thread (discussion thread) at the forums

External links

  • 42P15.1 at Heinrich Koenig's Game of Life Object Catalogs