1.2.13. Alternative proofs that every u, v-walk contains a u, v-path (Lemma 1.2.5). a) (ordinary induction) Given that every walk of length 1-1 contains a path from its first vertex to its last, prove that every walk of length / also satisfies this. b) (extremality) Given a u, v-walk W, consider a shortest u, u-walk contained in W.