Automata Theory Questions and Answers – DFA Processing Strings

This set of Automata Theory Multiple Choice Questions & Answers (MCQs) focuses on “DFA Processing Strings”.

1. The password to the admins account=”administrator”. The total number of states required to make a password-pass system using DFA would be __________
a) 14 states
b) 13 states
c) 12 states
d) A password pass system cannot be created using DFA
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2. Which of the following is the corresponding Language to the given DFA?

a) L = {x ϵ {0, 1} * | x ends in 1 and does not contain substring 01}
b) L = {x ϵ {0,1} * |x ends in 1 and does not contain substring 00}
c) L = {x ϵ {0,1} |x ends in 1 and does not contain substring 00}
d) L = {x ϵ {0,1} * |x ends in 1 and does not contain substring 11}
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3. Let ∑= {a, b, …. z} and A = {Hello, World}, B= {Input, Output}, then (A*∩B) U (B*∩A) can be represented as:
a) {Hello, World, Input, Output, ε}
b) {Hello, World, ε}
c) {Input, Output, ε}
d) {}
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4. Let the given DFA consist of x states. Find x-y such that y is the number of states on minimization of DFA?

a) 3
b) 2
c) 1
d) 4
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5. For a machine to surpass all the letters of alphabet excluding vowels, how many number of states in DFA would be required?
a) 3
b) 2
c) 22
d) 27
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Answer: a
Explanation:

6. For the DFA given below compute the following:
Union of all possible combinations at state 7,8 and 9.

a) {aba, ac, cc, ca, cb, bc, bab, ca}
b) {bab, bc, ac, aba, ca, aac, ccb}
c) {cc, ca, cb, aba, bab, ac}
d) {aba, ac, cc, ca, cb, bc, bab, caa}
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7. Given L= {Xϵ∑*= {a, b} |x has equal number of a, s and b’s}.
Which of the following property satisfy the regularity of the given language?
a) Regularity is dependent upon the length of the string
b) Regularity is not dependent upon the length of the string
c) Can’t be said for a particular string of a language
d) It may depend on the length of the string
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8. Given:
L= {xϵ∑= {0,1} |x=0n1n for n>=1}; Can there be a DFA possible for the language?
a) Yes
b) No
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9. δ(A,1) = B, δ(A,0) =A
Δ (B, (0,1)) =C
δ(C,0) = A (Initial state =A)
String=”011001” is transit at which of the states?
a) A
b) C
c) B
d) Invalid String
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Sanfoundry Global Education & Learning Series – Automata Theory.
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