- overview 실제 컴퓨터가 너무 복잡하니까, 계산이론 모델로 추상화하자! 가장 단순한 모델로 시작 ~ finite automata / finite automaton * finite automata - good model but limited amount of memory * finite automata --> pushdown automata (* stack) --> turing machine (*stack, tree) ▶ Example - controlling a toll gate / an automatic door ▶ DFA : Deterministic finite automata▷ definition - set of state - rules ( transition function) - alph..