Backtracking

Backtracking refers to an iterative process used in reading: it consists of trying out a sequence until it fails, going back to the last move in the sequence for which an alternative has not yet been tried, and repeating the process with the new move.

Backtracking requires mental discipline and a good memory in humans and intensive processing in computers but is needed to evaluate a dynamic property. To avoid backtracking, it is sometimes possible to formulate an equivalent static property, as in Benson's Theorem saying that a group is pass-alive (dynamically defined) if it satisfies his definition of unconditional life in terms of eyes of chains (statically defined).