Quasi stable outcomes in the assignment game

There is a great deal of literature on matching, theoretical, and empirical, concerning stable assignments and mechanisms that achieve them. The starting point of this study is an interesting question about assignment procedures: given a situation where some agents (the senior workers) on one side have a priority status, which changes the classical theory. The core of game may not be stable. We prove the existence of a quasi stable constrained core. This constrained core may not be a lattice but it is a finite and disjoint union of complete lattices that check the properties of the core's classical assignment game. We study the manipulability questions that derive.