Rotor
The rotor on an oscillator refers to its cells that change state at some point during its evolution. This term was coined by Allan Wechsler in 1994.[1] Unless the rule of evolution contains neighborhoods which simply bounce their cell back and forth, a changed cell implies that the neighborhood must also have changed. Conway's Life meets this requirement since birth requires three neighbors and two or three for maintainance. Once born, were that cell to die, those numbers must have changed, implying another, contiguous, change.
In summary, rotor cells must be adjacent to one another; possibly occurring only in isolated pairs. Some possibilities, including categories which have been given names, are listed in the following table.
The volatility of an oscillator is a measure of its relative rotor size.
| example / category | comment | image |
|---|---|---|
| Beacon | small oscillator, period 2 2-cell rotor |  |
| Great on-off | the same rotor as the preceding with a much larger stator |  |
| Blinker | small stator, period 2 4-cell rotor |  |
| Smiley | pure rotor, period 8 |  |
| Circle of fire | exterior rotor, period 2 |  |
| Babbling brook | single long rotor chain |  |
References
- DRH-oscillators.rle -- Dean Hickerson's oscillator collection header