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.
|LifeHistory example: 7-glider synthesis|
(click above to open LifeViewer)
RLE: here Plaintext: here
LifeViewer also supports [R]History which has the same additional states for any Life-like rule.
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:
- State 0: dead, as in Conway's Game of Life.
- State 1: alive, as in Conway's Game of Life.
- State 2: history/envelope: shows whether a dead cell was ever alive.
- State 3: marked alive; enters state 4 upon death.
- State 4: marked dead; enters state 3 upon birth.
- State 5: start alive; enters state 4 upon death.
- State 6: boundary; never changes state, used for separating objects in stamp collections. All living cells adjacent immediately die.
This last property of state 6 can be used to create patterns such as conduits, oscillators and guns that do not function in ordinary Life; however, this is not typically done, as the rule's primary purpose is to annotate Life patterns.
LifeHistory patterns can be saved in extended RLE format.
- Martin Grant (May 3, 2010). "The "Gray Cells" in LifeHistory Rule". Retrieved on June 5, 2019.