Practice Questions

Duration: 6 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Paper 1 | General Studies: State Wise GK
  3. Paper 1 | Information and Communication Technology: Role of Internet and Web Services, Security in Mobile and Wireless Computing
  4. Paper 1 | Current Affairs: GK- Current Affairs
  5. Paper 2 | Discrete Mathematical Structure: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Probability
  6. Paper 2 | Digital Computer Organization And Architecture: Number System, Number Representation, Sequential Circuits, Combinational Circuit, Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Register Transfer and Microoperations, Control Unit Design, Programming the Basic Computer
  7. Paper 2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  8. Paper 2 | Programming Languages & Object-Oriented Programming Concepts: Java, OOPS with C++, Java Fundamentals, Array, String, IO & References
  9. Paper 2 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  10. Paper 2 | Data Structure And Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Minimum Spanning Trees, Advanced Algorithms
  11. Paper 2 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Unix OS
  12. Paper 2 | Theory Of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Complexity Theory
  13. Paper 2 | Compiler Design: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization, Run Time Environment
  14. Paper 2 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Transaction Management, Concurrency Control, Database Recovery, Database Security & Authorization, Enhanced Data Models
  15. Paper 2 | Computer Network And Information Security: Introduction to CN, Data Communication, Application Layer, Hardware basics, Cyber Threats and Malware Attacks, Network Security, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP
  16. Paper 2 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  17. Paper 2 | Current Trends & Technologies: Emerging Tech Trends, Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Planning, Multi Agent Systems, Fuzzy Sets, Natural Language Processing, Artificial Neural Networks, Genetic Algorithms, Artificial Intelligence, Data Warehousing & Mining, Electronic Data Interchange and E-Commerce, Terms & Abbreviations
  18. Paper 2 | Full Length Mock Tests:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture provides a comprehensive guide on removing left recursion from Context-Free Grammars (CFGs), a fundamental requirement for constructing top-down parsers like recursive descent parsers. The instructor begins with the standard algorithm for immediate left recursion, demonstrating it on a classic arithmetic expression grammar. He then advances to more complex scenarios, including ambiguous grammars and indirect left recursion, illustrating how to substitute non-terminals to expose hidden recursion before applying the elimination technique. The visual board work clearly shows the step-by-step transformation of production rules, making the abstract process concrete for students.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces a grammar with immediate left recursion: E -> E + T / T, T -> T * F / F, F -> (E) / id. He identifies E -> E + T as the source of left recursion. He applies the standard transformation algorithm: E -> T E' and E' -> + T E' / epsilon. Similarly, he transforms T -> F T' and T' -> * F T' / epsilon, while keeping F -> (E) / id unchanged. This section establishes the foundational method for eliminating immediate left recursion by factoring out the recursive part into a new non-terminal E'. The board clearly displays the original grammar in orange and the transformed grammar in blue. The instructor underlines the recursive part.

  2. 2:00 – 5:00 02:00-05:00

    The lecture progresses to a more ambiguous grammar: E -> E + E / E * E / (E) / id. The instructor rewrites this to remove left recursion, resulting in E -> (E) E' / id E' and E' -> + E E' / * E E' / epsilon. He then tackles another example: R -> R * / R R / (R) / id. He transforms it into R -> (R) R' / id R' and R' -> * R' / R R' / epsilon. Finally, he addresses a list grammar: S -> (L) / a, L -> L, S / S. He transforms L into L -> S L' and L' -> , S L' / epsilon to remove the left recursion in L, ensuring the grammar is no longer left-recursive. The instructor uses underlining to highlight the recursive parts of the productions.

  3. 5:00 – 5:38 05:00-05:38

    The final example involves indirect left recursion: S -> A a B, A -> S A c / a, B -> B a / b. The instructor substitutes S into A, revealing A -> A a B A c / a. He then removes left recursion from A, resulting in A -> a A' and A' -> a B A c A' / epsilon. He then substitutes A back into S. Alternatively, he substitutes A into S to get S -> S A c a B / a a B, then removes left recursion from S, resulting in S -> a a B S' and S' -> A c a B S' / epsilon. He also handles B -> B a / b by transforming it to B -> b B' and B' -> a B' / epsilon. The board shows the substitution process clearly. He underlines the recursive parts.

The lesson systematically builds from simple immediate left recursion to complex indirect cases. By substituting non-terminals, hidden left recursion is exposed and then eliminated using the standard algorithm, ensuring the grammar is suitable for recursive descent parsers. The visual progression on the whiteboard reinforces the logical steps required for each transformation, providing a clear roadmap for students to follow when dealing with similar grammatical structures in their own studies.

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