For purposes of figuring out when the chain is going to fall off of Dr. Turing’s bicycle, then, everything we need to know about the bicycle is contained in the values of [theta] and of C . That pair of numbers defines the bicycle’s state. The bicycle has as many possible states as there can be different values of ([theta], C ) but only one of those states, namely (0, 0), is the one that will cause the chain to fall off onto the road.