LifeHistory

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LifeHistory is a multistate CA rule supported by Golly and LifeViewer, equivalent to two-state B3/S23 Life but with several additional states intended for annotation purposes. A "history" state records whether an off cell has ever turned on in the past, and other states allow on and off cells to be permanently or temporarily marked, without affecting the evolution of the pattern.

x = 37, y = 36, rule = LifeHistory 14.ABA$14.B2AB$15.A3B$16.4B$17.4B$18.4B2.D2BD$5.BA4.B7.3B3D2B3D$4.ABA B2.3B7.BD8BD$5.2A6B8.B3D2B3D$5.9B5.5B4DB$4.11B4.10B$3.6BA6B.B.5B2D4B$ 3.7BA12BD2BD5B$2.6B3A13B2D7B$3.9BA9B.9B$4.8B2A7B2.7B$5.6BABA7B3.6B$7. 13B4.7B$7.3B.9B5.2B.4B$6.4B.10B8.4B$5.4B3.9B9.4B$4.4B5.8B10.4B$3.4B6. 6B13.4B$2.4B9.4B14.B3A$.A3B11.4B14.A2B$B2AB13.4B14.A$ABA15.4B$19.4B$ 20.4B$21.4B$22.4B$23.4B$24.4B$25.3BA$26.B2AB$27.ABA! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 THEME 10 WIDTH 480 HEIGHT 480 ]]
LifeHistory example: 7-glider synthesis
of xs26_4aarggraa4zw4aa4/b3s23
(click above to open LifeViewer)

LifeViewer also supports [R]History which has the same additional states for any Life-like rule.

Details

LifeHistory is based on HistoricalLife, a 3-state rule with an additional dead state showing whether a given cell was ever alive. It has seven states:

  1. State 0: dead, as in Conway's Game of Life.
  2. State 1: alive, as in Conway's Game of Life.
  3. State 2: history/envelope: shows whether a dead cell was ever alive.
  4. State 3: marked alive; enters state 4 upon death.
  5. State 4: marked dead; enters state 3 upon birth.
  6. State 5: start alive; enters state 4 upon death.
  7. State 6: boundary; never changes state, used for separating objects in stamp collections.

LifeHistory patterns can be saved in extended RLE format.

External links