Regular expression Session 2020-21

1. Regular expressions are used to represent which language

• Recursive language

• Context free language

• Regular language

• All of these

Which of the following operation can be applied on regular expressions?

• Union

• Concatenation

• Closure

• All of these

The set of all strings over ∑ = {0,1} in which all strings that beings and ends with 0 is

• 0(0+1)0

• 00

• 00(0+1)0

• All of these

The set of all strings over ∑ = {a,b} in which all strings having bbbb as substring is

• (a+b)* bbbb (a+b)*

• (a+b)* bb (a+b)*bb

• bbbb (a+b)*

• bb (a+b)*

The set of all strings over ∑ ={a,b} in which a single a is followed by any number of b’s a single b followed by any number of a’s is:

• ab* + ba*

• ab*ba*

• a*b + b*a

• None

The set of all strings over ∑ = {a,b} in which all strings of a’s and b’s ending in bb is

• ab

• a*bbb

• (a+b)* bb

• All of these

Which of the following identity is wrong?

• R + R = R

• (R*)* = R*

• ɛR = Rɛ = R

• ØR = RØ = RR*

Which of the following statement is true?

• Every language that is defined by regular expression can also be defined by finite automata

• Every language defined by finite automata can also be defined by regular expression

• We can convert regular expressions into finite automata

• All of these

If P, Q, R are three regular expressions and if P does not contain a then the equation R = R + RP has a unique solution given by

• R = QP*

• R = P*Q

• R = RP

• None

If P, Q, R are three regular expressions and if P does not contain ____________ then the equation ___________ has a unique solution given by R=QP*

• One, R=Q+PQ

• Null, R=Q+RP

• Null, R=Q+QP*

• Null, R=QP*