Automata Theory Multiple Choice Questions on “Regular Language & Expression”.
1. A regular language over an alphabet a is one that can be obtained from
a) union
b) concatenation
c) kleene
d) All of the mentioned
Answer: d
Clarification: None.
2. Regular expression {0,1} is equivalent to
a) 0 U 1
b) 0 / 1
c) 0 + 1
d) All of the mentioned
Answer: d
Clarification: All are equivalent to union operation.
3. Precedence of regular expression in decreasing order is
a) * , . , +
b) . , * , +
c) . , + , *
d) + , a , *
Answer: a
Clarification: None.
4. Regular expression Φ* is equivalent to
a) ϵ
b) Φ
c) 0
d) 1
Answer: a
Clarification: None.
5. a? is equivalent to
a) a
b) a+Φ
c) a+ϵ
d) wrong expression
Answer: c
Clarification: Zero or one time repetition of previous character .
6. ϵL is equivalent to
a) ϵ
b) Φ
c) L
d) Lϵ
Answer: c,d
Clarification: None.
7. (a+b)* is equivalent to
a) b*a*
b) (a*b*)*
c) a*b*
d) none of the mentioned
Answer: b
Clarification: None.
8. ΦL is equivalent to
a) LΦ
b) Φ
c) L
d) ϵ
Answer: a,b
Clarification: None.
9. Which of the following pair of regular expression are not equivalent?
a) 1(01)* and (10)*1
b) x(xx)* and (xx)*x
c) (ab)* and a*b*
d) x+ and x*x+
Answer: c
Clarification: (ab)*=(a*b*)*.
10. Consider following regular expression
i) (a/b)* ii) (a*/b*)* iii) ((ϵ/a)b*)*
Which of the following statements is correct
a) i,ii are equal and ii,iii are not
b) i,ii are equal and i,iii are not
c) ii,iii are equal and i,ii are not
d) all are equal
Answer: d
Clarification: All are equivalent to (a+b)*.