In the theory of cellular automata, an oscillator is a pattern that repeats itself after a fixed number of generations; that number is called its period. A cellular automaton is called omniperiodic if there exist oscillators of all periods. At the turn of the millennium, only twelve oscillator periods remained to be found in Conway's Game of Life. The search has finally ended, with the discovery of oscillators having the final two periods, 19 and 41, proving that Life is omniperiodic. Besides filling in the missing periods, we give a detailed history of the omniperiodicity problem and the strategies used to solve it, summarising the work of a large number of people in the decades since the creation of Life.
  • davel [he/him]@lemmy.ml
    ·
    11 months ago

    I must be missing something. If CGL has already been proven to be Turing complete, and if Turing completion implies omniperiodicity (which seems trivially true), then what was the point of this exercise?

    • qwertyasdef@programming.dev
      ·
      11 months ago

      I don't think Turing-completeness implies omniperiodicity. I'm imagining a cellular automaton which follows Game of Life rules on even-numbered generations and does nothing on odd-numbered generations, which is trivially Turing-complete because it's just Conway's Game of Life if you ignore every other generation, but also trivially has no odd-period oscillators.