Which of the following are correct for regular expressions?
a. φ + L = L + φ = L
b. εL = Lε = L
c. φL = Lφ = φ
d. φL = Lφ = L
Choose the correct answer from the options given below:
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Correct answer: B. a, b and c only
Explanation
φ is the identity for union, ε is the identity for concatenation and φ annihilates concatenation. d contradicts c.More Theory of Computation and Compilers questions
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