VTU Computer Science (Semester 5)
Formal Languages and Automata Theory
December 2013
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) Mention the difference between DFA,NFA and ?-NFA.
6 M
1 (b) Design a DFA which accept set of all string of 0's and 1's beginning with a 1 that,when interpreted as a binary integer ,is a multiple of 5.For example strings 101,1010 and 1111 are in the language :0,100,0101 and 111 are not
6 M
1 (c) Convert the following NFA to DFA using construction method:
δ 0 1
→p {p,q} {p}
q φ {r}
*r {p,r} {q}

8 M

2 (a) Consider the following ?-NFA:

Compuer the ?-closure of each state .
Give the set of all string of lenghth 3 or less accepted by the automation
Convert the automation to DFA.
δ a b
{r} {q} {p,r}
q φ {p} φ
*r {p,q} {r} {p}

8 M
2 (b) Give the regular expression for the following languages:
L={a n b m:n ?4,m ?2};
L={w:w?(0,1)* and |w| mod 3=0}
4 M
2 (c) mention the application of regular expression
2 M
2 (d) prove that every language defined by RE is also defined by some finite automataion
6 M

3 (a) State and prove that pumping lemma of regular languages
6 M
3 (b) Obatin the regular expression or distinguish ?Minimize the following DFA using table finite automation using state climatation method

4 M
3 (c) When two sates are equivalent or distingushable ?minimize the following DFA using table filling algorithm
δ 0 1
→q1 q2 q3
q2 q3 q5
*q3 q4 q3
q4 q3 q5
*q5 q2 q5

10 M

4 (a) Decline CFG .Design a context free grammer for the language :
L={a i bj ck, where i=J+k.j,k?0}
L={0 n+21n:n ?1}
8 M
4 (b) What is an ambigous grammer? Show that grammer shown below is ambigous
S?AB|aaB
A&rarr|a
B ?b
6 M
4 (c) Consider the grammer
E?+EE/*EE/-EE/x/y
Find the left most derivation ,right most derivation and parsetree for the string "+ * - xyxy.
6 M

5 (a) Discuss the language accepted by a PDA .design to PDA to accept the following language L=02n 1n n?1}.draw the transmistion diagram for the constructed PDA ,Also show the moves made by PDA for the string "000011"
14 M
5 (b) Convert the following grammer to PDA that accept the same by empty stack: S?aABB/aAA
A?aBB/a
B?bBB/a
C ?a
6 M

6 (a) What are useless production ? Eliminate ? unit and unless production from following grammer
A?bA/Bba/aa
B ?aba/b/D ,
C ?CA/AC/B ,
D ?a /?
10 M
6 (b) Define chomskey normal form .convert the following CFG to CNF
S ?aSb/ab /Aa
A ? aab
6 M
6 (c) prove that the context free languages are closed under union
4 M

7 (a) Design a turing machine to accept the languages L={ww R:w?(a,b)*}.write its transition diagram .Also show the sequence of moves made by the TM for the string "aabbaa"
14 M
7 (b) Define turing machin .Explain with a diagram general structure of multiple turning machine
6 M

Write short note on:
8 (a) Recursive language
5 M
8 (b) universal turing machine
5 M
8 (c) Post correspondance problem
5 M
8 (d) Application Of Context free grammer
5 M



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