VTU Computer Science (Semester 5)
Formal Languages and Automata Theory
June 2015
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary


1 (a) Design a DFA to read strings mode up of letters 'CHARIOT' and recognize these strings that contains the word 'CAT' as a substring.
8 M
1 (b) Draw DFA to accept the language L= { ω: ω has add number of } and followed by even number of 0's. Completely define DFA and transition function.
6 M
1 (c) Convert the following NFA to its equivalent DFA.
6 M

2 (a) Probe that if L=L(A) for some DFA, then there is a regular expression R such that L=L(R).
6 M
2 (b) For the following DFA, obtain regular expression Rij(0) and Rij(1).
States Σ  
0 1
→ q1 q2 q1
q2 q3 q1
q3 q3 q2
9 M
2 (c) Construct NFA for regular expression V=(01+10).
5 M

3 (a) State and prove pumping Lemma for regular languages.
5 M
3 (b) Show that L={An| u ≥ 0} is not regular.
5 M
3 (c) Construct 0 minimum automation equivalent to given automation 'M' whose transition table given below.
States Input
0 1
→q0 q0 q3
q1 q2 q5
q2 q3 q4
q3 q0 q5
q4 q0 q6
q5 q1 q4
q6 q1 q3
10 M

4 (a) What is grammar? Explain the classification of grammars with examples.
7 M
4 (b) Obtain the grammar to generate the following languages.
i) L= {ω : na (ω) mod 2=0 where ω ∈ (a,b)*}
ii) L={ω : ω is a palindrome , where ω ∈ (a,b)*
iii) L=anb2n| u ≥ 1.
6 M
4 (c) Show that the following grammar is ambiguous:
S → a|Sa| bSS | Ssb | SbS.
7 M

5 (a) Construct PDA for the language and simulate this PDA
L={aibjck | j=i+k,i,k≥0.
10 M
5 (b) Define PDA. Explain the language accepted by PDA.
5 M
5 (c) Explain the PDA with two stocks.
5 M

6 (a) Simplify the grammar by eliminating useless productions
S AB
A → a
B → C | b
C → D
D → E | bC.
E → d | Ab.
6 M
6 (b) Convert the following CFG and CNF.
S → aB | bA
A → a | aS | bAA
B → b | aS | aBB.
6 M
6 (c) Prove that context free language are closed under union, concatenation and star.
8 M

7 (a) Explain the programming techniques for turning machine.
10 M
7 (b) Construct a TM for L={ au bu cu | u ≥ 1}. Give the graphical representation for the obtained TM.
10 M

Explain the following
8 (a) Post correspondence problem.
5 M
8 (b) Recursively enumerable language.
5 M
8 (c) Recursively language.
5 M
8 (d) Universal language.
5 M



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