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Consider the languages Σ = {a, b} and Γ = { Ø, λ, ∪, (, ), a, b }.  Let L ⊆ Σ such that for all x ∈ L, x is a regular expression for Σ.

Is the language Γ regular?

>>8
an equal number of left and right parentheses, which cannot be expressed by a finite state acceptor
You're correct, but this is not a formal argument. Try using the pumping lemma