For each of the following languages A, write a regular expression r such that L(r) = A, and then give an NFA Nr such that L(Nr) = A. Well, if you give a DFA, that counts as an NFA, but in one or two cases you may find the NFA easier to build especially once you have r. For part (b), note that a string can be broken uniquely into maximal blocks of consecutive letters. For instance, in Tennessee the blocks are T, e, nn, e again, ss, and ee.

(a) The language of strings over {a, b} in which every b is followed immediately by at least one a.

(b) The language of strings over {a, b} in which every a belongs to a block of at least 2 as and every b belongs to a block of at least 3 bs.

(c) The language of strings over {a, b} with no block of 3 bs, and in which every block of 2 bs has an odd number of chars before it.