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[1] and named by Bill Gosper.

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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

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.[2]

The period 9 version of Jolson
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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. Dean Hickerson's oscillator stamp collection. Retrieved on March 14, 2020.
  2. Mark Niemiec (August 14, 2019). Re: Oscillator Discussion Thread (discussion thread) at the forums
  • 42P15.1 at Heinrich Koenig's Game of Life Object Catalogs
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