Definition of Finite Automata Automata Theory by ComputeNow - August 8, 2018August 12, 20180 Definition of Finite Automata: A finite automata (FA) is a simple idealized machine used to recognize patterns within input taken from some character set (or alphabet) C. The job of an FA is to accept or reject an input depending on whether the pattern defined by the FA occurs in the input. A finite automaton consists