An FSM is defined by a list of its states, its initial state, and the conditions for each transition. The behavior of state machines can be observed in many devices in modern society that perform a predetermined sequence of actions depending on a sequence of events with which they are presented. The computational elements of finite model theory pdf distinction means there are computational tasks that a Turing machine can do but a FSM cannot. A turnstile, used to control access to subways and amusement park rides, is a gate with three rotating arms at waist height, one across the entryway.
Initially the arms are locked, blocking the entry, preventing patrons from passing through. After the customer passes through, the arms are locked again until another coin is inserted. Unlocks the turnstile so that the customer can push through. When the customer has pushed through, locks the turnstile.
Each arrow is labeled with the input that triggers that transition. A transition is a set of actions to be executed when a condition is fulfilled or when an event is received. When the system is in the “CD” state, the “next” stimulus results in moving to the next track. Identical stimuli trigger different actions depending on the current state.
The complete action’s information is not directly described in the table and can only be added using footnotes. SDL embeds basic data types called “Abstract Data Types”, an action language, and an execution semantic in order to make the finite state machine executable. There are a large number of variants to represent an FSM such as the one in figure 3. Finite state machines can be subdivided into transducers, acceptors, classifiers and sequencers.
Each state of an FSM is either “accepting” or “not accepting”. The example in figure 4 shows a finite state machine that accepts the string “nice”. In this FSM, the only accepting state is state 7. Finite State Machine that accepts exactly that set. The start state can also be an accepting state, in which case the automaton accepts the empty string. An example of an accepting state appears in Fig. 00, 010, 1010, 10110, etc.