4-state busy beaver w/ time diagram. Vertical axis is the actual tape, and horizontal is steps advanced.
Some context: a "busy beaver" of n states is the turing machine of n states that halts that produces either 1) the most number of 1's, or 2) takes the most number of steps. The former is more commonly referred to as busy beaver, and the number of 1's produced is given by the function Σ(n). The latter is also called busy beaver, but for specificity is called frantic frog sometimes. The number of steps of the frantic frog is given by S(n). While the frantic frog turing machine and busy beaver turing machine for n states are not necessarily the same, they usually are. For instance, the 4-state busy beaver is the 4-state frantic frog. This scratch project shows the behavior of the 4-state BB/FF from first step to halting. Σ(4) = 13 and S(4) = 107.
