Formal Languages Questions
The main difference between a PDA (Pushdown Automaton) and a finite automaton lies in their computational power and memory capabilities.
A finite automaton, also known as a finite state machine, is a computational model that operates on an input string and transitions between states based on the current input symbol. It has a fixed amount of memory and can only recognize regular languages, which are languages that can be described by regular expressions or regular grammars.
On the other hand, a PDA is an extension of a finite automaton that includes an additional stack memory. This stack allows the PDA to store and retrieve symbols, enabling it to recognize context-free languages, which are more powerful than regular languages. PDAs can handle nested structures and keep track of multiple levels of recursion, making them more expressive than finite automata.
In summary, the key difference between a PDA and a finite automaton is the presence of a stack memory in PDAs, which allows them to recognize context-free languages, while finite automata can only recognize regular languages.