Practice Problem on First Function

Duration: 8 min

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Module outline

HPSC Interview Preparation: Interview Preparation
Python Language: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis, DSA using Python
Data Structure & Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Sorting Algorithms, Minimum Spanning Trees, Time Complexity Analysis, Graph Theory, Shortest Path Algos
Computer Networks: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Security
Computer System & Organisation: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Programming the Basic Computer
Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, SQL, File Organization & Indexing, Transaction Management, Concurrency Control
Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling
Digital Logic & Circuits: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
Theory Of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Pushdown Automata & CFG, Turing Machines, Moore & Mealy Machines
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
Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management, Data Warehousing & Mining
Introduction to Emerging Trends: Emerging Tech Trends
Digital Society & Cyber Law: Society, Law & Ethics
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AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a detailed lecture on Compiler Design, specifically focusing on the calculation of First and Follow sets for context-free grammars. The instructor systematically works through multiple examples of increasing complexity, demonstrating how to derive these sets for various production rules. The session begins with simple recursive grammars involving epsilon productions and progresses to standard arithmetic expression grammars. The lecture concludes with a theoretical overview of the formal rules used to calculate First sets for both terminals and non-terminals.

Chapters

0:00 – 2:00 00:00-02:00
The instructor begins with a grammar: S -> AaB / Bb, A -> bA / epsilon, B -> cB / epsilon. He calculates First(A) as {b, epsilon} and First(B) as {c, epsilon}. For First(S), he analyzes the productions S -> AaB and S -> Bb. Since A can derive epsilon, 'a' is added to First(S). Since B can derive epsilon, 'b' is added. The final set written on the board is First(S) = {b, a, c}. He then transitions to a second example: S -> AB, A -> a / epsilon, B -> b / epsilon. He determines First(A) = {a, epsilon} and First(B) = {b, epsilon}. He explains that First(S) becomes {a, b, epsilon} because both A and B can derive epsilon, allowing the derivation to continue or terminate early.
2:00 – 5:00 02:00-05:00
The lecture progresses to a more complex chain: S -> ABCDE. The non-terminals A, B, C, and E have epsilon productions (A -> a/epsilon, B -> b/epsilon, C -> c/epsilon, E -> e/epsilon), while D -> d is a terminal production. The instructor calculates First(A)={a, epsilon}, First(B)={b, epsilon}, First(C)={c, epsilon}, First(D)={d}, and First(E)={e, epsilon}. He determines First(S) = {a, b, c, d} because the derivation stops at D. Next, he analyzes S -> aAB / BA, A -> BA / epsilon, B -> AB / a / epsilon. He finds First(B) = {a, epsilon} and First(A) = {a, epsilon}. Consequently, First(S) is derived as {a, epsilon} based on the union of the first symbols of the productions.
5:00 – 8:28 05:00-08:28
The instructor presents S -> AA, A -> aA, A -> b. He calculates First(S) = {a, b} and First(A) = {a, b}. He then moves to a list grammar: S -> (L) / a, L -> SL', L' -> ,SL' / epsilon. He calculates First(L') = {,, epsilon}. He then tackles a standard arithmetic expression grammar: E -> TE', E' -> +TE' / epsilon, T -> FT', T' -> *FT' / epsilon, F -> (E) / id. He calculates First(F) = {(, id}, First(T') = {*, epsilon}, First(T) = {(, id}, First(E') = {+, epsilon}, and First(E) = {(, id}. Finally, he shows a slide defining the rules for First(alpha), covering terminals, epsilon productions, and sequences of non-terminals, explaining that First(alpha) is the set of all terminals that may begin in any sentential form derived from alpha.

The video effectively bridges practical examples with theoretical definitions. By starting with simple recursive structures and moving to complex chains and standard expression grammars, the instructor demonstrates the iterative nature of First set calculation. The final slide reinforces the logic used throughout the examples, providing a formal framework for students to apply to new problems. The progression from specific calculations to general rules ensures a comprehensive understanding of the topic.