Let V,C be the Roman-alphabet vowels and consonants, respectively, and let A be both together, the whole alphabet thus. (Consider "y" to be a consonant.) Remember that V (etc.) is sometimes used as shorthand for V, the language comprising one-letter words made from V. Recall that we use U for union of languages and for the empty word. Postfix is "zero or more" and postfix + is "one or more" repetitions. How many words does A have? (Equivalently, how many words does A have?) How many words does C have? (Equivalently, how many words does C have?) How do you write the language of all words that begin and end with vowels, and never have two consonants together? How do you write the language of all words with at most one vowel? How do you write the language of all words with at least one vowel? How do you write the language of all words that never have two consonants together? How many letters does V have? (Equivalently, how many words does V have?) How do you write the language of all words with exactly one vowel? How do you write the language of all words that begin and end with a vowel, and strictly altemate between consonants and vowels? Choose... Choose... Choose... Choose... Choose... Choose... Choose... Choose... Choose...