Elena Molis

Stability in decentralized roommate markets.
Supervisors: Elena Iñarra and Conchi Larrea

Committee members

  • Bettina Klaus (Maastricht University), 
  • Robert Irving (University of Glasgow), 
  • Jean Lainé (Ecole Nationale de la statistique et de l'analyse de l'information), 
  • Jordi Masso (Universitat Autònoma de Barcelona), 
  • Federico Valenciano (UPV/EHU)



 This thesis is devoted to exploring decentralized roommate markets, where agents seek and are matched with each other by forming successive blocking pairs, specially in those cases in which there is no stable matchings. In the first chapter, we define some specific matchings, called P-stable matchings, which exist for any roommate market, and show that from any matching there exists a path that reaches one of these matchings. In the second chapter, we analyze absorbing sets as a solution for roommate problems with strict preferences. The solution provides the set of stable matchings when this is nonempty and some matchings with interesting properties otherwise. In particular, all matchings in an absorbing set have a set of "satisfied" agents paired in the same stable manner. In case of multiple absorbing sets we find that any two absorbing sets differ only in how these satisfied agents are matched with each other. Last chapter presents experimental data concerning agents’ rationality in order to achieve a stable matching in decentralized one-sided matching. An analysis of the roommate problem under both complete and incomplete information suggests that agents behave as expected, forming profitable blocking pairs to improve on their status quo. Nevertheless, a small proportion of irrational agents suffices to prevent a stable matching from being maintained once it is achieved.


First affiliation

 Facultes universitaires Saint-Louis (Brussels, Belgium)


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