Which one of the following languages over Σ = {𝑎, 𝑏} is NOT context-free?

August 2, 2023

Q. Which one of the following languages over Σ = {𝑎, 𝑏} is NOT context-free?

(A) {𝑤𝑤^𝑅 |𝑤 ∈ {𝑎, 𝑏}^∗}

(B) {𝑤𝑎^𝑛𝑏^𝑛𝑤^𝑅 |𝑤 ∈ {𝑎, 𝑏}^∗, 𝑛 ≥ 0}

(D) {𝑎^𝑛𝑏^𝑖 | 𝑖 ∈ {𝑛, 3𝑛, 5𝑛}, 𝑛 ≥ 0}

Ans: {waⁿw^Rbⁿ ⏐ w ∈ {a, b}*, n≥ 0}