This is a question regarding computer science computational theory and DFA/NFA. If the alphabets are limited as {a, b}, please write the regular expression for a string language that cannot accept single 'a' or odd length of consecutive 'a' in a row. It can contain 'a' only when there is even length of consecutive 'a' in a row. For instance, "bababaab" or "baaab" are rejected, but "baabbb" or "bbbbb" is good. ALSO please draw picture of DFA (definite finite automata) with only 3 states (include dead state if exists) for this language (NOT NFA!) Thank you!