English

The random stable roommates problem typically has no solution

Combinatorics 2026-01-13 v1 Probability

Abstract

Assume that n=2kn = 2k potential roommates each have an ordered preference of the n1n-1 others. A stable matching is a perfect matching of the nn roommates in which no two unmatched people prefer each other to their matched partners. In their seminal 1962 stable marriage paper, Gale and Shapley noted that not every instance of the stable roommates problem admits a stable matching. In the case when the preferences are chosen uniformly at random, Gusfield and Irving predicted in 1989 that there is no stable matching with high probability for large nn. We prove this conjecture and show that for nn sufficiently large, the probability there is a stable matching is at most n1/17n^{-1/17}.

Keywords

Cite

@article{arxiv.2601.07612,
  title  = {The random stable roommates problem typically has no solution},
  author = {Byron Chin and Marcus Michelen},
  journal= {arXiv preprint arXiv:2601.07612},
  year   = {2026}
}

Comments

18 pages + 3 page appendix

R2 v1 2026-07-01T09:00:51.880Z