Time-Reversal in Conway's Life as SAT

This paper describes a translation of the time-reversal problem in Life to propositional satisfiability. Two useful features of this translation are: that the encoding is linear (in both variables and clauses) with respect to the number of cells in the original problem; and, it can be used to generate problem instances that are known a priori to be satisfiable. The problem is shown to have statistically defined hard regions where instances are on average more difficult than in other regions.