Practice Question - 3

Duration: 4 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. English Language: Vocabulary, Noun, Adjectives, Tenses, Pronoun, Adverb, Preposition, Conjunction, Active Passive Voice (Voice), Articles, Direct and Indirect Speech, Sentence Correction (Error Correction), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Sentence Completion (Fill in the blanks), Cloze Test (Cloze Passage)
  3. Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Puzzle Solving (Puzzles), Seating Arrangements, Blood Relations, Syllogisms, Inequality, Directions (Direction Test), Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Clock, Calendar, Analytical Reasoning (Counting Figures Reasoning), Selection Decision Table (Decision Making), Cubes & Dices, Machine Input-Output
  4. Quantitative Aptitude: Ratio and Proportion (Ratios), Data Interpretation, Mixture and Alligation, Permutation and Combination, Number System, Sequence and Series (Series), Speed Time and Distance, Algebra, Speed Mathematics and Basic Mathematics, Percentage, Average, Time and Work, Simple Interest and Compound Interest, Profit and Loss, Age Problems, Partnership, Mensuration and Geometry, Probability, IBPS Specific Videos
  5. Data Structures - Professional Knowledge: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  6. Algorithms- Professional Knowledge: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  7. Python- Professional Knowledge: Python for Placements by Yash Sir, Python Basics
  8. Operating System- Professional Knowledge: Introduction to OS, Process Management, CPU Scheduling, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management
  9. DBMS + SQL- Professional Knowledge: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), File Organization & Indexing, SQL, Transaction Management, Concurrency Control
  10. Computer Networks- Professional Knowledge: Introduction to CN, Data Communication, Net Layer: IP Addressing, Net Layer: IPv4 & Proto, Application Layer, Hardware basics, Network Security
  11. Software Engineering- Professional Knowledge: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  12. Computer Organization & Microprocessor- Professional Knowledge: Basics of COA, Cache Memory Organization, Programming the Basic Computer
  13. Digital Logic Design- Professional Knowledge: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  14. Theory of Computation- Professional Knowledge: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Regular Language Properties, Pushdown Automata & CFG, Turing Machines
  15. Compiler Design- Professional Knowledge: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Intermediate Code Gen, Code Optimization
  16. Programming Languages- Professional Knowledge: C Programming by Yash Sir, Object Oriented Programming (OOPS), Programming in C++, Java, C Language Core
  17. Emerging Tech- Professional Knowledge: Emerging Tech Trends
  18. Artificial Intelligence: Artificial Intelligence
  19. Unit Test - Professional Knowledge:
  20. Full Length Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture presents a step-by-step construction of a Pushdown Automaton (PDA) for the language $L = \{ww^r \mid w \in \{a, b\}^*\}$. The instructor defines the language as a string $w$ concatenated with its reverse $w^r$. He illustrates this with the example $w = aaba$, resulting in $aabaabaa$. The lecture focuses on drawing the PDA state diagram, starting with an initial state $q_0$ that pushes input symbols onto the stack. He introduces a non-deterministic transition to state $q_1$ to guess the midpoint and match the reverse string by popping symbols. The session concludes with a theoretical overview of Non-Deterministic PDAs (NPDA), defining them using 7 tuples and explaining the transition function that allows movement to multiple states.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the problem statement: "Construct pda that accepts a language $L = \{ww^r \mid w \in \{a, b\}^*\}$". He explains the language structure where a string $w$ is followed by its reverse $w^r$. He provides an example: $w = aaba$ and $w^r = abaa$, forming $aabaabaa$. He begins the PDA construction by drawing the initial state $q_0$ with a self-loop. He writes transition rules like $a, a / aa$, $a, b / ab$, $b, a / ba$, and $b, b / bb$. These transitions show the PDA pushing input symbols onto the stack to store $w$. He also draws a transition from $q_0$ to state $q_1$ labeled $a, a / \epsilon$ and $b, b / \epsilon$, representing the non-deterministic choice to start matching the reverse string.

  2. 2:00 – 4:08 02:00-04:08

    The instructor refines the PDA diagram, circling the transition from $q_0$ to $q_1$ to highlight the non-deterministic guess of the string's midpoint. He explains that in state $q_1$, the PDA matches input against the stack. He draws a self-loop on $q_1$ with transitions $a, a / \epsilon$ and $b, b / \epsilon$, popping the stack if inputs match. A transition to final state $q_2$ with $\epsilon, Z / Z$ indicates acceptance. The video then shifts to a slide titled "Non-Deterministic PDA". It defines an NPDA using 7 tuples and highlights the transition function $\delta: Q imes (\Sigma \cup \{\epsilon\}) imes \Gamma o 2^{Q imes \Gamma^*}$. The instructor explains that an NPDA can move to multiple states for a given input and stack symbol, essential for languages like palindromes where the midpoint is unknown. He notes that the rest of the tuples remain the same as a DPDA.

The lecture bridges practical construction and theoretical definition. It demonstrates how non-determinism allows PDAs to handle unknown midpoints in palindromes by pushing the first half and non-deterministically switching to pop and match the second half. The session concludes by formalizing this concept through the mathematical definition of an NPDA.

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