Since the signi?cance of the states represented by the nodes of these transition graphs is arbitrary, we will allow ourselves to use any ?nite set (such as {A,B,C,D,E, F,G,H} or even pairs of the sort we used to label the LTk transition graphs) to represent them. The key characteristics of these graphs are the fact that the state set encodes everything that is signi?cant about the computation and the fact that there are ?nitely many of those states. For that reason, the corresponding automata are known as Finite State Automata (FSAs). These come in two main varieties, Deterministic Finite State Automata (DFAs) and Non-Deterministic Finite State Automata (NFAs). We will focus initially on the deterministic variety. When we are talking about ?nite state automata in general, without regard to whether they are deterministic or not, we will use the term FSA.