@zareen said in CS606 Assignment 1 Solution and Discussion:
Use Subset Construction algorithm to find DFA for the NFA constructed in Task 1.
The resulting DFA is
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CS606 – Compiler Construction
Assignment # 03
Fall 2019
Total marks = 20
Deadline Date
22nd January, 2020
Please carefully read the following instructions before attempting assignment.
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OBJECTIVE
Objective of this assignment is to increase the learning capabilities of the students about
• Context-Free Grammars
• LL(1) Table constructions
• Follow Sets
NOTE
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Questions No 01 12+8=20 Marks
Consider the grammar given below:
S → XaXb
S → Yb
X → €
Y → €
Where € (epsilon) is empty string.
a) Find First and Follow sets for above grammar. [12]
b) Construct LL (1) parsing table. [8]
Good Luck!
The FIRST of a sentential form is the set of terminal symbols that lead any sentential from derived from the very first sentential form. In this particular case X and Y only derive the empty string and as a result the empty string is the FIRST set of both non-terminal symbols X and Y. The FIRST of S, however, includes “a” as in the first production once can derive a sentential form that starts with an “a” given that X can be replaced by the empty string. X similar reasoning allows you to include “b” in the FIRST(S).
summary: FIRST(X) = {e}, FIRST(Y) = {e}, FIRST(S) = {a, b}
The FOLLOW set of a non-terminal symbol is the set of terminals that can appear after that non-terminal symbol in any sentential form derived from the grammar’s start symbol. By definition the follow of the start symbol will automatically include the $ sign which represents the end of the input string. In this particular case by looking at the productions of S one can determine right away that the follow of X includes the terminal “a” and “b” and that the FOLLOW of Y includes the terminal “b”. Given that the non-terminal S does not appear in any productions, not even in its own productions, the FOLLOW of S is only $.
summary: FOLLOW(S) = {$}, FOLLOW(X) = {a, b}, FOLLOW(Y) = {b}.
b) YES, because the intersection of the FIRST for every non-terminal symbol in empty. This leads to the parsing table for this LL method as indicated below. As there is no conflict in entry then grammar is clearly LL (1).
[23/01, 21:33] Waqas Ahmad: a b $
S S→XaXb S → Yb
A X→ε X→ε
B Y→ε
@ramsha-kanwal
Simple reply the topic and upload file
ab to so hi jana chaye fr
@Nabeel-Chaudhary btay?
@Nabeel-Chaudhary w8 kru k so jau?
mery pas file hai pr mujhy idhr uplod ni krni aa rahi
@Nabeel-Chaudhary plz send me solution file at [email protected]
@Nabeel-Chaudhary bhai agr ap k pas file ha to send kr do plz
@ramsha-kanwal Give me your email or something i will send you a file
allah hi puchy ga
bta dy file hai k ni plz
@ramsha-kanwal File hai hi nahi in k pas
@zareen This does not make any sense. I also downloaded this type of sketch from internet. Its so confusing. The thing is our assignment is gone.
plz file send kr dy