LifeHistory is a multistate rule equivalent to two-state Conway's Game of Life with several additional states for annotation. 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 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, and will never reappear during evolution.
- State 6: boundary; never changes state, and all adjacent living cells die in the next tick.
LifeHistory is based on HistoricalLife, a 3-state rule with an additional dead state showing whether a given cell was ever alive.
The state 6 is primarily for separating objects in stamp collections. It can also be used to create patterns such as conduits, oscillators and guns that do not function in ordinary Life, but this is not its intended use.
For any 2-state range-1 cellular automaton (up to MAP rules) with rulestring [R], a rule [R]History can also be defined with the same additional states. This class of rules can be supported by LifeViewer and version 4.0+ of Golly via "Super" algorithm, and patterns under which can be saved in extended RLE format.
- Rule:LifeHistory - a rule table for LifeHistory.