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Formal Languages and Logic/Finite state automata
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deterministic finite state automaton A deterministic finite state automaton (DFA for short) is a quintuple , where is a finite set, is a finite alphabet, is a function, , and .
state Let be a deterministic finite state automaton. Then a state of is an element of .
initial state Let be a deterministic finite state automaton. Then the initial state of is .
transition function Let be a deterministic finite state automaton. Then is the transition function.
accepting state Let be a deterministic finite state automaton. Then an accepting state is an element of .
every accepting state is a state Let be a deterministic finite state automaton. Then every accepting state of is a state.
This is because .
generalized transition function Let be a deterministic finite state automaton. Then the generalized transition function is the function defined on by induction on word length as thus:
for a singleton word ,
whenever , then
language accepted by a deterministic finite state automaton Let be a finite state automaton. The language accepted by the deterministic finite state automaton by is defined to be
.
finite state automata accept precisely regular languages Whenever is a finite state automaton, the language accepted by is regular. Whenever is a regular language, there exists a finite state automaton that accepts it.
Let first be a finite state automaton. Define a Chomsky grammar as follows: , and the productions shall be given by