Automata Theory and Application

An automaton with a finite number of states is called a Finite Automaton (FA) or Finite State Machine (FSM).
Formal definition of a Finite Automaton
An automaton can be represented by a 5-tuple (Q, ∑, δ, q0, F), where −
Q is a finite set of states.
∑ is a finite set of symbols, called the alphabet of the automaton.
δ is the transition function.
q0 is the initial state from where any input is processed (q0 ∈ Q).
F is a set of final state/states of Q (F ⊆ Q).