Q. 65 If L is a regular language over ∑ = {a, b}, which one of the following languages is NOT regular?
(A) L⋅ LR {xy ⏐ x ∈ L, yR∈ L}
(B) Suffix (L) = {y ∈ ∑* ⏐ ∃x ∈ ∑* such that xy ∈ L}
(C) Prefix (L) = {x ∈ ∑* ⏐ ∃y ∈ ∑* such that xy ∈ L}
(D) {wwR ⏐ w ∈ L}
Answer: (D)
Explanation:
