Let G be a k-extendable, bipartite graph with bipartition (X,Y). By Lemma 2.1, κ(G)≥k+1. Hence for each non-empty subset S of X such that |X|−k<|S|≤|X|, |X|−κ(G)+1<|S|≤|X|. Hamiltonian and long cycles in bipartite graphs In this section, we show a suffici...