Restricted complementarity and paths to stability in matching with couples

Abstract

We study matching with couples problems where hospitals have one vacant position. We introduce a constraint on couples’ preferences over pairs of hospitals called restricted complementarity, which is a “translation” of bilateral substitutability in matching with contracts. Next, we extend Klaus and Klijn’s (2007) path to stability result by showing that if couples’ preferences satisfy restricted complementarity, then from any arbitrary matching, there exists a finite path of matchings where each matching on the path is obtained by “satisfying” a blocking coalition for the previous one and the final matching is stable.