When using the pumping lemma with length to prove that the language L = {ab"a, n>0} is nonregular, the following approach is taken. Assume Lis regular. Then there exists an FA with k states which accepts L. We choose a word w = abka = xyz, which is a word in L. Some options for choosing xyz exist 1. x=y= a, z = bka 2. x = a, y = bP, z = bk-pa, for some p > 0, p0, p+q