A note on example 13.3, pages 285-286 of Rich (1st edition): Part of the explanation in the last bulleted item is confusing. She is saying that in this case, pumping in (q > 1) would not work because the strings would still be in L, but pumping out (q = 0) would take us out of the language because there would be fewer a's than b's. In the next sentence (begins with "Moew importantly") she is sayig that in the pumping theorem, |vxy| must be <= k, and that is not true here (since all of the b's are included in x, and vy cannot be empty), so this case can simply be ignored.