Uses of automata and compiler design?

Answer 1

Automata is the science of state machines. State machines are (programming) entities with defined states and procedures (rules) for going from one state to another. An example might be an elevator. You define the various states, i.e. open, closed, which floor, which direction, what call buttons are pressed, etc. Then you define the rules, such as not changing directions when there is a call in the same direction. You would not define a rule for going from the first to the third floor, but you would define a rule for going from one floor to an adjacent floor. State machines are well suited to compiler design. If, for instance, you are parsing an expression, you would expect a binary operator to be surrounded by two operands. If you were parsing a while loop, you would expect the while keyword to be followed by an expression in parenthesis, followed by a statement. In automata, you design the basic machine, and provide the rules for going from one state to another. For a compiler, this makes it (relatively) easy to make changes to language syntax because you need only deal with rules, rather than thinking about wide scope procedural changes.