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Push Down Automata (PDA). Automata -- FA, PDA, TM Generator: CFG -- Recognizer: PDA Model of nondeterministic top-down parser. Difference between FA & PDA. We can see the difference from the following informal definition of PDA (additional memory): (1) an input string
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Push Down Automata (PDA) Automata -- FA, PDA, TM Generator: CFG -- Recognizer: PDA Model of nondeterministic top-down parser
Difference between FA & PDA • We can see the difference from the following informal definition of PDA (additional memory): (1) an input string (2) a read head to exam input one cell at a time (3) a finite state machine to control moves (4) LIFO push down stack • DPDA is not equivalent to NPDA in representing CFL