GATE (Graduate Aptitude Test in Engineering) Computer Science & IT (CS) Theory of Computation-Context Free Languages and Push-Down Automata Study Material (Page 7 of 17)

Choose Programs:

🎓 Study Material (1190 Notes): 2024-2025 Syllabus

Rs. 1000.00 -OR-

3 Year Validity (Multiple Devices)

Topic-wise Notes & SampleDetails

🎯 302 Numeric, 2894 MCQs (& PYQs) with Full Explanations (2024-2025 Exam)

Rs. 650.00 -OR-

3 Year Validity (Multiple Devices)

CoverageDetailsSample Explanation

Help me Choose & Register (Watch Video) Already Subscribed?

Pushdown Automaton

Edit

Pushdown Automaton

  • Pushdown automata (PDAs) can be thought of as combining an NFA “control-unit” with a “memory” in the form of an infinite stack. PDAs are more powerful than FAs, being able to recognize languages that FAs cannot. In fact, the set of languages that can be recognized by PDAs are the context-free languages.
  • Pushdown automata are nondeterministic finite state machines augmented with additional memory in the form of a sta…

… (576 more words, 10 figures) …

Subscribe (by clicking here) to view full notes and track progress.

Pushdown Automaton: Definition, Instantaneous Description

Edit

Definition

A pushdown automaton reads a given input string from left to right. In each step, it chooses a transition by indexing a table by input symbol, current state, and the symbol at the top of the stack. A pushdown automaton can also manipulate the stack to push a particular symbol to the top of the stack, or to pop off the top of the stack. The automaton can alternatively ignore the stack, and leave it as it was.

Definition – A Pushdown automata can be formally described in the form of a 7-tuple given as

… (222 more equations, 24 figures) …

Subscribe (by clicking here) to view full notes and track progress.