Initially, the symbol 0 Converting a CFG into a PDA. Main idea: The PDA simulates the leftmost derivation on a given w, and upon consuming it fully it either arrives at acceptance (by empty stack) or non-acceptance. CS Automata Theory Instructor: S. Akshay IIT Bombay, IndiaModuleFinite automata with a stack Extending DFA/NFA with additional storage: stackPushdown Converting a CFG into a PDA. Main idea: The PDA simulates the leftmost derivation on a given w, and upon consuming it fully it either arrives at acceptance (by empty stack) or non Push-Down Automata DFA could not accept languages such as 0n1n because they have no memory We can give an NFA memory – stack Examine the next symbol in the input, and Introduction n Pushdown automata are used to determine what can be computed by machines. Initially, the stack holds a special symbol Zthat CS Automata Theory Instructor: S. Akshay IIT Bombay, IndiaModuleFinite automata with a stack Extending DFA/NFA with additional storage: stackPushdown automata: NFA with one (LIFO-)stackCon guration, move and examplesAcceptance condition: by nal state and empty stackDeterministic Pushdown automata n More capable than finite-state machines but less capable than Turing machines. n A type of Nondeterministic Pushdown Automata Pushdown automata provide abstract models of computation. Example PDA accepting =
Initially, the symbol 0 Converting a CFG into a PDA. Main idea: The PDA simulates the leftmost derivation on a given w, and upon consuming it fully it either arrives at acceptance (by empty stack) or non-acceptance. CS Automata Theory Instructor: S. Akshay IIT Bombay, IndiaModuleFinite automata with a stack Extending DFA/NFA with additional storage: stackPushdown Converting a CFG into a PDA. Main idea: The PDA simulates the leftmost derivation on a given w, and upon consuming it fully it either arrives at acceptance (by empty stack) or non Push-Down Automata DFA could not accept languages such as 0n1n because they have no memory We can give an NFA memory – stack Examine the next symbol in the input, and Introduction n Pushdown automata are used to determine what can be computed by machines. Initially, the stack holds a special symbol Zthat CS Automata Theory Instructor: S. Akshay IIT Bombay, IndiaModuleFinite automata with a stack Extending DFA/NFA with additional storage: stackPushdown automata: NFA with one (LIFO-)stackCon guration, move and examplesAcceptance condition: by nal state and empty stackDeterministic Pushdown automata n More capable than finite-state machines but less capable than Turing machines. n A type of Nondeterministic Pushdown Automata Pushdown automata provide abstract models of computation. Example PDA accepting =
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