Pushdown Automata

Unit 4 Study Material

Download detailed notes, important questions and PYQ analysis for IT503(A) Theory of Computation Unit 4.

📚 PDA

Pushdown Automata uses stack memory to recognize context-free languages.

⚙️ DPDA / NPDA

DPDA is deterministic while NPDA allows multiple possible moves.

🔁 CFG ↔ PDA

Context Free Grammar can be converted into PDA and PDA into CFG.

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Detailed Notes

Complete notes on Pushdown Automata, formal definition of PDA, closure properties, examples of PDA, deterministic PDA, non-deterministic PDA, PDA to CFG and CFG to PDA.

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Important Questions

Important RGPV questions on PDA design, DPDA, NPDA, stack operations, acceptance by PDA, CFG to PDA conversion and PDA to CFG conversion.

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PYQ Analysis

Previous year questions and repeated topics from Theory of Computation Unit 4 for quick exam revision.

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Unit 4 Topics

Introduction to PDA

Pushdown Automata

Formal Definition of PDA

PDA Components

Input Tape

Stack Memory

Transition Function of PDA

Instantaneous Description

Acceptance by Final State

Acceptance by Empty Stack

Closure Property of PDA

Examples of PDA

Designing PDA

Deterministic Pushdown Automata

DPDA

Non-Deterministic Pushdown Automata

NPDA

DPDA vs NPDA

Conversion of PDA to CFG

Conversion of CFG to PDA

PDA for Balanced Parentheses

PDA for CFL