a) Explain why R= 1"(00 1")" is an ambiguous block decomposition. b) Let S be the set of all strings that begin with a 1, have no blocks of 0's of length divisible by 3, and such that there are no blocks of l's of length exactly 2. Write an unambiguous regular expression that produces S and prove it is unambiguous. Compute the generating series s(r) with respect to the number of l's in the strings.