O. Favaron et al., HAMILTONIAN PROPERTIES OF BIPARTITE GRAPHS AND DIGRAPHS WITH BIPARTITE INDEPENDENCE .2., SIAM journal on discrete mathematics, 6(2), 1993, pp. 189-196
This paper studies the bipartite graphs G in which alpha(BIP)(G), the
maximum order of an induced balanced bipartite subgraph without edges,
is equal to 2. When its order is at least 10, it is shown that G cont
ains a Hamiltonian path, provided that it is connected, and that, if i
ts minimum degree is at least 2, then it is bipancyclic. Similar resul
ts concerning the bipartite digraphs D in which alpha(BIP)2(D) are giv
en, and the maximum order of an induced balanced bipartite subdigraph
without 2-cycles, is equal to 2.