For the classical marriage model (introduced in Gale and Shapley, 1962) efficiency and envy-freeness are not always compatible, i.e., fair matchings do not always exist. However, for many allocation of indivisible goods models (see Velez, 2008, and references therein), fairness can be restored...

We consider one-to-one, one-sided matching (roommate) problems in which agents can either be matched as pairs or remain single. We introduce a so-called bi-choice graph for each pair of stable matchings and characterize its structure. Exploiting this structure we obtain as a corollary the "lone...