A deterministic finite automaton is represented formally by a 5-tuple (Q,Σ,δ,q0,F), where:
- Q is a finite set of states.
- Σ is a finite set of symbols, called the alphabet of the automaton.
- δ is the transition function, that is, δ: Q × Σ → Q.
- q0 is the start state, that is, the state of the automaton before any input has been processed, where q0∈ Q.
- F is a set of states of Q (i.e. F⊆Q) called accept states.