Problem
I. Write formal description of the set containing the string {aba}.
II. Sequences and Tuples: What is the power set of B = {x, y}
III. Strings and Languages: For alphabet Σ = {a, b, c}, suppose x ∈ Σ ∗ and |x| = 5. Give a string x 0 that is a substring of x and has the following property: Among all substrings of x, x 0 is both a prefix of x and a suffix of x, and is the longest substring of x.