Formal Languages Questions
The main difference between a pushdown automaton and a Turing machine lies in their computational power and the resources they have access to.
A pushdown automaton (PDA) is a type of finite state machine that has an additional stack memory. It can read input symbols, transition between states, and push or pop symbols onto or from the stack. PDAs are capable of recognizing context-free languages, which are a subset of formal languages.
On the other hand, a Turing machine (TM) is a more powerful computational model that consists of an infinite tape divided into cells, a read/write head that can move along the tape, and a control unit that determines the machine's behavior. TMs can read and write symbols on the tape, transition between states, and perform computations. They have the ability to recognize and decide any recursively enumerable language, which includes both context-free and context-sensitive languages.
In summary, while both pushdown automata and Turing machines are used to recognize formal languages, Turing machines have a broader computational power and can solve more complex problems than pushdown automata.